zsh: turn off unwanted/broken completion
zsh: turn off unwanted/broken completion

As noted here:

http://unix.stackexchange.com/questions/132290/git-completion-with-zsh-filenames-with-spaces-arent-being-escaped-properly

There is something fishy about the `compadd -Q` calls in the Git-completion
script at `/usr/local/share/zsh/site-functions/_git`. I presume these are being
installed by the Homebrew Git package, or something. Whatever the case, I am
just going to hack the unwanted completion out of the way, and use the standard
Zsh one.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent