Enable tmux to send-prefix using C-a a

* It's useful when you have a tmux session into another tmux session
  (ie. via ssh).
Add puppet module
Fix gitconfig colors causing iTerm with solarized to show diffs incorrectly
Changed reference to prezto master
Go back to using skwp prompt for rvm-prompt integration
Merge pull request #402 from imobach/master

Enable tmux to send-prefix using C-a a
Added syntax highlightning for tmux.conf

(cherry picked from commit 50be196f972349e6bfbeda5a198ad98bc7586ebe)
Spring rspec alias
Make :Gsesarch way faster - requires to :BundleUpdate to get latest skwp/greplace.vim
Merging from master