Bash config & aliases. Major vim mapping changes.

* Use vi line editing in bash.
* New git aliases and an alias for 'bundle update'.
* Set mapleader to ','.
* Change all mappings that begun with ',' to begin with <leader>.
* Change all mapings using map, imap and nmap to their nonrecursive
  counterparts noremap, inoremap and nnoremap.
* Make arrow keys useful as hell. Can move around and indent lines and
  switch b/w tabs now.