Add fogbugz/fogbugz.go from hookyapp
Support for resolving fogbugz cases on github push events

Currently, fogbugz config is global. I'd like to add per-repo
fogbugz config support in the future but it's just not necesary
for us right now.

Should probably also make the regex that extracts bug numbers
configurable.
Merge pull request #1 from sandyarmstrong/push

Support for resolving fogbugz cases on github push events