Adds uglify2 to build config whitelist.

Author: gcirne

lib/requirejs/rails/config.rb

@@ -83,6 +83,7 @@ def initialize
         skipModuleInsertion
         skipPragmas
         uglify
+        uglify2
         useStrict
         wrap
       }
@@ -101,7 +102,7 @@ def build_config
                                                     "modules" => [ { 'name' => 'application' } ]
         self[:build_config].merge!(self.user_config).slice!(*self.build_config_whitelist)
         case self.loader
-        when :requirejs 
+        when :requirejs
           # nothing to do
         when :almond
           mods = self[:build_config]['modules']