Category Pages support- prototype

- loading category pages as a normal articles
- below article- list of its member pages
- searching category member pages
- animations (load more, searching) 
Prototype- needs opinions.
Do we have to wrap `Em.$.ajax` with `Em.RSVP.Promise`? I recall @hakubo telling something about getting rid off the 2nd 'cause `$.ajax` returns a promise anyway.