Fixes a typo in bash_profile, swaps SnipMate for UltiSnips
More Vim keybindings, bash_profile fix

I hardcoded the path to z.sh so when I upgraded z to the latest version,
it broke. It has been changed to use the backtick construct to find out
the HomeBrew prefix value, i.e: `brew --prefix`.
Updated vimrc a little. Not much really