Ajaxified likes

fixes #801

Decompose each like subaction into its own method, each method can be called directly and will produce a generic response. Handles both ajax calls and normal calls. If we do move to php 5.2 the response method can be easily adapted to return more data as a json object.

Hooks now need to return an array of data.

There are a few new language strings so the usual check needs to be done.