Turn off pair matching highlighting in vim

My vim experience was very slow, and after profiling it turned out to be
pair matching highlighting. This commit turns this feature off.

To profile, I did the following:

  :profile start profile.log
  :profile func *
  :profile file *
  " At this point do slow actions
  :profile pause
  :noautocmd qall!"

via http://stackoverflow.com/a/12216578/18986