Added hyperlinks to FogBugz case(s) in GitHub PR commit target references

Fixed bug with forge dependency

Now includes a quick-picker for common cases in the extension popup, currently static but could be made dynamic at some point.

And more importantly, it is now prettier than ever. Thanks to @ambroselittle .

Added support for automatic case tracking/work against cases in:

• Source and Target commit/branch references in GitHub Pull Requests (see https://github.com/CentralReach/FogMachine#github-url)
• Call/video conference URLs - if you join a conference call that has what can be inferred as a case number in the first URL segment, we'll work against that case (see https://github.com/CentralReach/FogMachine#conference-url)
• Static URL to case mapping - for specific URLs you visit that you want to track to a specific case. (see https://github.com/CentralReach/FogMachine#static-case-map)

Add the extension as usual from here:

https://chrome.google.com/webstore/detail/jfmcegeknnnnnmjhcnhljhiinfonmfid

Fixes:

• #8