fix r9e_strip_fromp_path in ZSH

$path is an array containing the elements from $PATH in ZSH. This caused errors in the old r9e_strip_from_path function in ZSH.
Add some /usr/local paths to FPATH in ZSH

These directories contain completion functions installed by homebrew on Mac OS X. So when they exist it propably makes sense to include them in the FPATH.