[JRO] Upgrade and use timeago properly

* Update timeago to 1.3.0 from 0.11.4
* Change app config to use UTC instead of EST
* Remove tz offset nonsense from app js and let timeago do its job.

I can't believe it took me this long to take care of this. Dumb Joel.
[JRO] Extract to decorators

Things have gotten well past the point where a bunch of
methods need to be extracted to decorators. Post, Topic, 
and User are all a little bit leaner thanks to new 
decorators.

TODO: Extract the common timeago helpers to a shared module