Bump Firefox to 20.0.1

Casks/firefox.rb

@@ -1,8 +1,8 @@
 class Firefox < Cask
-  url 'http://download.cdn.mozilla.net/pub/mozilla.org/firefox/releases/19.0.2/mac/en-US/Firefox%2019.0.2.dmg'
+  url 'http://download.cdn.mozilla.net/pub/mozilla.org/firefox/releases/20.0.1/mac/en-US/Firefox%2020.0.1.dmg'
   homepage 'http://www.mozilla.org/en-US/firefox/'
-  version '19.0.2'
+  version '20.0.1'
-  sha1 'b2b64726b2552b9f28c36e8219ff3246a6a15ea4'
+  sha1 '510b7e53be4b120ca2e277dec3a64a09f64c8ed8'
 
   link :app, 'Firefox.app'
 end