Added ETag support from http://dev.rubyonrails.org/changeset/6158
1) Upgrade Rails to 1.2.3 2) Revert RedCloth to previous version (who %#$@ cares?) 3) Preserve the Rails Security fix to vendor/rails/actionpack/lib/action_controller/caching.rb from Revision 80.
Sync with latest Instiki Trunk (Updates Rails to 1.2.2)
