Remove a bunch of unused packages and swap some for others:

 - Unused:
     fullscreen-mode
     slime

 - Swap for others:
     paredit - swap for smartparens
    git-gutter - swap for diff-hl since supports svn as well

 - Also remove fill-column-indicator since it doesn't play nicely with
   company-mode (or auto-complete-mode for that matter)