added ability to specify a PHP method to change tag case
added ability to specify a PHP method to change tag case

git-svn-id: 14431f16c86e063b591b7186ad64c5043b5760e0@13286 ee427ae8-e902-0410-961c-c3ed070cd9f9

weaverryan/sfDoctrineActAsTaggablePlugin,weaverryan/sfDoctrineActAsTaggablePlugin