Allow forcing bottle installation.

Library/Homebrew/bottles.rb

@@ -17,6 +17,7 @@ def install_bottle? f, warn=false
     and f.downloader.local_bottle_path
 
   return false if ARGV.build_from_source?
+  return true if ARGV.force_bottle?
   return false unless f.pour_bottle?
   return false unless f.build.used_options.empty?
   return false unless bottle_current?(f)

Library/Homebrew/extend/ARGV.rb

@@ -149,6 +149,10 @@ module HomebrewArgvExtension
     end
   end
 
+  def force_bottle?
+    include? '--force-bottle'
+  end
+
   # eg. `foo -ns -i --bar` has three switches, n, s and i
   def switch? switch_character
     return false if switch_character.length > 1