fix(labels): pass github api credentials if available

This gets around the API limiting for unauthorized requests to api.github.com.
You need to set your client_id and client_secret with...

```
localStorage.setItem('github.client_id', "....");
localStorage.setItem('github.client_secret', "....");
```
Merge pull request #10 from petebacondarwin/github_api_fix

fix(labels): pass github api credentials if available