Clean up ,rev.

Move configuration to the ini file and allow for the querying of any
github repository. Example configuration below, where the first two are
*very* likely to be what's used.

;-----------------------------------------------------------------------------
; GitHub
;-----------------------------------------------------------------------------

; github.url
;    Support Github Enterprise installs
github.url = "https://github.com"

; github.api_url
;    Endpoint for the Github API
github.api_url = "https://api.github.com"

; github.default_project
;    The default project to query
github.default_project = "habari/system"
Clean up #issue.

Some extra smarts because Habari's issues are not in the default repo.
Better error checking needed.
Fix docblock.
Better handle issue default.

I'll need it for stats too.
Add a basic stats command.

Needs nicer format, report the days in the message, possibly deal with
timezones, include a commit count.
Merge pull request #1 from michaeltwofish/github_plus_plus

Improvements to the Github plugin
Format stats output more nicely.
Make stats return commit count.

This isn't DRY with respect to changeset or rev.
Remove outdated trac stuff.
Make channels where speaking without a prefix is ok configurable.

For the ini file:

```
; github.speak_channels
;    Comma-separated list of channels where it's okay to respond when a prefix isn't used
github.speak_channels = "#habari,#racerbot,#mikelietz"
```
DRY the API calls a little.
Merge pull request #2 from michaeltwofish/github_plus_plus

More clean up and extend stats
Move the API to its own class.
Update changeset and rev for the API class.
Merge pull request #3 from michaeltwofish/github_plus_plus

Move API into its own class
Get the milestone with stats.
Merge pull request #4 from michaeltwofish/github_plus_plus

Get the milestone with stats.
Add fortnight, for fun.
Fix milestone URL.
Merge pull request #5 from michaeltwofish/github_plus_plus

Fix milestone URL.