Var goes back in the keg. Fixes Homebrew/homebrew#67

I'm not sure about this still, as if you uninstall mysql do you want to lose
all the var stuff it created? Maybe. Probably not.

But there were issues unresolved having it in the unversioned-keg. So I'd
rather look at this again later, and fix the bugs without hacks for now.

Library/Homebrew/formula.rb

@@ -96,7 +96,7 @@ class Formula
   def info; prefix+'share'+'info' end
   def include; prefix+'include' end
   def share; prefix+'share' end
-  def var; prefix.parent+'var' end
+  def var; prefix+'var' end
 
   # reimplement if we don't autodetect the download strategy you require
   def download_strategy