Encoding error on Windows

Hey! Love your project so far, just got it all up and running.
The thing is, though, when running it the first time I encountered an annoying error.

Full traceback:

```bash
Traceback (most recent call last):
File "C:\Users\orel-\AppData\Local\Programs\Python\Python35\Scripts\statuspage-script.py", line 11, in
load_entry_point('statuspage==0.8.1', 'console_scripts', 'statuspage')()
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\click\core.py", line 722, in __call__
return self.main(*args, **kwargs)
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\click\core.py", line 697, in main
rv = self.invoke(ctx)
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\click\core.py", line 1066, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\click\core.py", line 895, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\click\core.py", line 535, in invoke
return callback(*args, **kwargs)
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\statuspage\statuspage.py", line 65, in create
run_create(name=name, token=token, systems=systems, org=org, private=private)
File "c:\users\orel-\appdata\local\programs\python\python35\lib\site-packages\statuspage\statuspage.py", line 276, in run_create
content=f.read(),
File "c:\users\orel-\appdata\local\programs\python\python35\lib\encodings\cp1252.py", line 23, in decode
return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 56487: character maps to
```

I googled a bit, and found [this topic on stackoverflow](https://stackoverflow.com/questions/9233027/unicodedecodeerror-charmap-codec-cant-decode-byte-x-in-position-y-character)

And it helped!
Basically I modified [this line](https://github.com/jayfk/statuspage/blob/master/statuspage/statuspage.py#L269) to also include `encoding="utf-8"` and it worked like a charm!

So now this code block looks like this

```python
# add all the template files to the gh-pages branch
for template in tqdm(TEMPLATES, desc="Adding template files"):
with open(os.path.join(ROOT, "template", template), "r", encoding="utf-8") as f:
repo.create_file(
path="/" + template,
message="initial",
content=f.read(),
branch="gh-pages"
)
```

Hope that helps!

Encountered on Windows 10 with Anniversary update in both ConEmu and Powershell. I use english locale in the system

Start in statuspage/statuspage.py around line 269, where run_create opens the template files during the create command. Reproduce the first-run flow on Windows and verify that template processing completes without the reported UnicodeDecodeError.

Written by the indexing model from the issue text.