Promtimer should support alternate address (was: promtimer issue working with remote AWS instances)

I was encountering an issue when starting promtimer against a remote AWS instance. I put a printf in urllib/request.py in do_open
```1346 try:
1347 try:
1348 print(f"{req.get_method()} {req.selector} {req.data} {headers}")
1349 h.request(req.get_method(), req.selector, req.data, headers,
1350 encode_chunked=req.has_header('Transfer-encoding'))
1351 except OSError as err: # timeout error
1352 raise URLError(err)
1353 r = h.getresponse()
```
and see this crash. Note the /pools/default/buckets is being done against the localhost (127.0.0.1) which is my mac. This is a single node, just created cluster so maybe that's a reason
```
steve.watanabe @ ~/promtimer/bin (master) $ ./promtimer --cluster ec2-52-23-193-116.compute-1.amazonaws.com:8091 --user Administrator --password asdasd
GET /pools/default/nodeServices None {'Host': 'ec2-52-23-193-116.compute-1.amazonaws.com:8091', 'User-Agent': 'Python-urllib/3.11', 'Connection': 'close'}
GET /pools/default/nodeServices None {'Host': 'ec2-52-23-193-116.compute-1.amazonaws.com:8091', 'User-Agent': 'Python-urllib/3.11', 'Authorization': 'Basic QWRtaW5pc3RyYXRvcjphc2Rhc2Q=', 'Connection': 'close'}
GET /pools/default/buckets None {'Host': '127.0.0.1:8091', 'User-Agent': 'Python-urllib/3.11', 'Connection': 'close'}
Traceback (most recent call last):
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1349, in do_open
h.request(req.get_method(), req.selector, req.data, headers,
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1282, in request
self._send_request(method, url, body, headers, encode_chunked)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1328, in _send_request
self.endheaders(body, encode_chunked=encode_chunked)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1277, in endheaders
self._send_output(message_body, encode_chunked=encode_chunked)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1037, in _send_output
self.send(msg)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 975, in send
self.connect()
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 941, in connect
self.sock = self._create_connection(
^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/socket.py", line 851, in create_connection
raise exceptions[0]
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/socket.py", line 836, in create_connection
sock.connect(sa)
ConnectionRefusedError: [Errno 61] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/Users/steve.watanabe/promtimer/bin/../promtimer/promtimer.py", line 336, in
main()
File "/Users/steve.watanabe/promtimer/bin/../promtimer/promtimer.py", line 302, in main
buckets = stats_sources[0].get_buckets()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/steve.watanabe/promtimer/promtimer/cbstats.py", line 412, in get_buckets
response = util.execute_request('{}:{}'.format(self.host(), self.port()),
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/steve.watanabe/promtimer/promtimer/util.py", line 139, in execute_request
response = opener.open(request)
^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 519, in open
response = self._open(req, data)
^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 536, in _open
result = self._call_chain(self.handle_open, protocol, protocol +
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 496, in _call_chain
result = func(*args)
^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1378, in http_open
return self.do_open(http.client.HTTPConnection, req)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1352, in do_open
raise URLError(err)
urllib.error.URLError:
```

I then add a second node to the cluster and try again. Note it uses a non-local IP address (172.31.15.151) but not the external one and so the connection times out.

```
steve.watanabe @ ~/promtimer/bin (master) $ ./promtimer --cluster ec2-52-23-193-116.compute-1.amazonaws.com:8091 --user Administrator --password asdasd
GET /pools/default/nodeServices None {'Host': 'ec2-52-23-193-116.compute-1.amazonaws.com:8091', 'User-Agent': 'Python-urllib/3.11', 'Connection': 'close'}
GET /pools/default/nodeServices None {'Host': 'ec2-52-23-193-116.compute-1.amazonaws.com:8091', 'User-Agent': 'Python-urllib/3.11', 'Authorization': 'Basic QWRtaW5pc3RyYXRvcjphc2Rhc2Q=', 'Connection': 'close'}
GET /pools/default/buckets None {'Host': '172.31.15.151:8091', 'User-Agent': 'Python-urllib/3.11', 'Connection': 'close'}
Traceback (most recent call last):
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/urllib/request.py", line 1349, in do_open
h.request(req.get_method(), req.selector, req.data, headers,
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1282, in request
self._send_request(method, url, body, headers, encode_chunked)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1328, in _send_request
self.endheaders(body, encode_chunked=encode_chunked)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1277, in endheaders
self._send_output(message_body, encode_chunked=encode_chunked)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 1037, in _send_output
self.send(msg)
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 975, in send
self.connect()
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/http/client.py", line 941, in connect
self.sock = self._create_connection(
^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/socket.py", line 851, in create_connection
raise exceptions[0]
File "/usr/local/Cellar/python@3.11/3.11.2_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/socket.py", line 836, in create_connection
sock.connect(sa)
TimeoutError: [Errno 60] Operation timed out
```

I skimmed the promtimer code and see it is using /pools/default/nodeServices

Running on my node
```
"thisNode": true,
"hostname": "172.31.15.151"

"hostname": "ec2-54-88-70-0.compute-1.amazonaws.com"
```
and
```
"hostname": "172.31.15.151"

"thisNode": true,
"hostname": "ec2-54-88-70-0.compute-1.amazonaws.com"
```
Having entered this issue perhaps there's two issues: 1) remote promtimer doesn't work against a node that doesn't have a "hostname" in the results from /pools/default/nodeServices and 2) ns_server may not be returning the right hostname...though I'm not sure how ns_server would know the IP isn't the external IP.