Add alias for HEAD checkout on Git
Add plugin for finding files and co-working

- ag.vim uses Ag to find files in a dir
- CoVim allows one to start a server and pair with another Vim user
  remotely.
Add hotkeys for split window usage and config editing

- ,c opens ~/.vimrc in a new tab
- ,s re-sources ~/.vimrc from anywhere
- ,w is just like Ctrl+w
- ,- makes the size of all splits on the screen equiv
Update Antigen.