Add numbers.vim to vundles.list

numbers.vim is a plugin that allows for easy switch between
absolute and relative line numbers.
A convenient shortcut: ,tn (toggle numbers) is provided to
switch between the two modes

Fixes #276

README.md

@@ -211,6 +211,8 @@ If you omit the key combo, you'll get a list of all the maps. You can do the sam
  * `Cmd-j` and `Cmd-k` to move up and down roughly by functions
  * `Ctrl-o` - Old cursor position - this is a standard mapping but very useful, so included here
  * `Ctrl-i` - opposite of Ctrl-O (again, this is standard)
+ * `,tn` - Toggles between absolute and relative line numbers
+ * `:NumbersEnable` - Enable automatic toggling between absolute (insert mode) and relative (normal mode) line numbers
 
 #### LustyJuggler