pushover priority 2 (emergency) is broken if you provide required expiry or retry

This is because unlike priority which is converted to an int
` priority = int(priority)`

causing
```
if not expire or expire > 86400:
TypeError: '>' not supported between instances of 'str' and 'int'
```

retry and expiry aren't. This fixes it (wrapping all int comparisons and the final data set in `int(..)`

```
if not retry or int(retry) < 30:
logging.getLogger(__name__).error(
'retry is less than 30 or is not set, '
'setting retry to 30 to comply with '
'pushover API requirements')
data['retry'] = 30
else:
data['retry'] = int(retry)

# Expire can not be more than 86400 (24 hours)
if not expire or int(expire) > 86400:
logging.getLogger(__name__).error(
'expire is greater than 86400 seconds or is not set,'
'setting expire to 86400 to comply with'
'pushover API requirements')
data['expire'] = 86400
elif int(expire) <= 86400:
data['expire'] = int(expire)
```