Mail related changes.

Add offlineimap and msmtp configs.  Cleanup mutt configs.

Changes inspired by Steve Losh post:

    http://stevelosh.com/blog/2012/10/the-homely-mutt/.
Add vim Yankring plugin.
Add vim sparkup bundle (Zen Coding port).
Vim snipmate plugin moved to the bundle.
Add Command-T vim plugin.
Update vim config.