Fixes installation procedure on Macs
Fixes installation procedure on Macs

pil's formula was recently removed from brew, and 'brew install pil' no longer
works.

gskielian/SimpleCV,jlegendary/SimpleCV,nils-werner/SimpleCV,sightmachine/SimpleCV,hurdlea/SimpleCV,jlegendary/SimpleCV,sightmachine/SimpleCV2,sightmachine/SimpleCV2,beni55/SimpleCV,onaclovtech/SimpleCV,beni55/SimpleCV,onaclovtech/SimpleCV,sightmachine/SimpleCV,jyt109/SimpleCV,nils-werner/SimpleCV,jyt109/SimpleCV,hayd/SimpleCV,gskielian/SimpleCV,hurdlea/SimpleCV,jlegendary/SimpleCV,hayd/SimpleCV,gskielian/SimpleCV,nils-werner/SimpleCV,jlegendary/SimpleCV,sightmachine/SimpleCV2,hayd/SimpleCV,hurdlea/SimpleCV,onaclovtech/SimpleCV,jyt109/SimpleCV,hayd/SimpleCV,beni55/SimpleCV,gskielian/SimpleCV,nils-werner/SimpleCV,tpltnt/SimpleCV,gskielian/SimpleCV,sightmachine/SimpleCV2,tpltnt/SimpleCV,sightmachine/SimpleCV,onaclovtech/SimpleCV,beni55/SimpleCV,sightmachine/SimpleCV,tpltnt/SimpleCV,jyt109/SimpleCV,sightmachine/SimpleCV,nils-werner/SimpleCV,hurdlea/SimpleCV,hurdlea/SimpleCV,hayd/SimpleCV,jlegendary/SimpleCV,beni55/SimpleCV,tpltnt/SimpleCV,tpltnt/SimpleCV,jyt109/SimpleCV,onaclovtech/SimpleCV