Manage Vim plugins with Vundle

- Remove git submodules
- Remove Pathogen
Clean up RubyGems config

- Shorten default gem list
- Install with --no-document flag
Clean up and strengthen git configs
Beef up .inputrc
Re-purpose .screenrc
Steal .hushlogin text from @mathiasbynens

Thanks Mat!
Refactor Zsh config to be more flexible

Influenced by @mathiasbynens' and @thoughtbot's
dotfile repos. Check them out.
Refactor bootstrap installers

Thanks again @thoughbot.