Use version 1.8 of ruby for bundle items

10.7 and 10.8 only include ruby 1.8, so all bundle items have been written to work with that. Optionally supporting ruby 1.9 and 2.0 is problematic as these versions are not fully backwards compatible.

 #ignore
Add syntax for commit message editing.

This is based on the git commit message syntax, and contains
all of the same features that make sense.
Exit gracefully when cancelling commit

TextMate treats any non-zero exit code as an error and will issue a warning dialog. If we decide to cancel the commit for some reason (e.g., due to conflicts), we should just let the user know and not TextMate via exit codes.
Update a comment to reflect the new behavior when canceling a commit

While we were here, fixed a few whitespace/alignment issues.
Enable diffs in Commit Window
Point to ruby 1.8 shim

Using a shim allows us to catch when 1.8 of ruby is not present and provide other options.

#ignore
Use requiredCommands to locate hg
Remove bash sourcing

Remove where no longer necessary, also remove rescan_project as this is automatic in 2.0. #ignore
Call commit window asynchronously in status view

Fixes #3