Adding Operating System info with report submission

adding operating system field to Diagnose bug more properly!

And here you're only returning the version, rather than os + version. Playing with the ua parser in the console should give you an idea of how to return something more useful:

``` python
>>> from ua_parser import user_agent_parser
>>> f = user_agent_parser.Parse('Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:33.0) Gecko/20100101 Firefox/33.0')
>>> f.get('os')
{'major': '10', 'patch_minor': None, 'minor': '9', 'family': 'Mac OS X', 'patch': None}
>>> f.get('os').get('family')
'Mac OS X'
>>> f.get('os').get('major')
'10'
>>> f.get('os').get('minor')
'9'
```

In this case, I'd probably expect to see "Mac OS X 10.9", so you'd have to combine `family`, `major` and `minor`.

If you look at a different UA-string, you can see that you probably only want to include extra info if it's not `None`:
``` python
>>> f = user_agent_parser.Parse('Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)')
>>> f.get('os')
{'major': None, 'patch_minor': None, 'minor': None, 'family': 'Windows', 'patch': None}
>>> 
```