Fix newly created topics display as unwatched

When submitting a new topic it would occasionally not display that
you were watching the title.  This was due to trying to read our own
writes, it works on a dev box but as soon as you get a slave db in there
we get intermittent errors.

Solve this by adding a new listener.  This new listener waits for PostRevision
instances to be created with appropriate change types and subscribes the user
to that change type.  It additionally informs the WatchedtopicItems object
that it should override this title.  The combination of the two allows the
TopicListQuery to appropriatly mark the title as watched without getting
a slave db involved.

This is also a little cleaner in terms of how the subscription gets triggered,
its centralized now rather than spread through the various Block instances.

Change-Id: I6e188544477156655ef5457b587fb20c06cd74ba
Hygiene: rename title-post to topic-title

This is called a topic title in the rest of the code base,
rename it within the notification parameters for consistency.

Also rename some variables in other places, again to topicTitle
to keep consistency.

Change-Id: I71045d041380bdd0a49e24c434f7719db021eff9
Merge "Fix newly created topics display as unwatched"
Merge "Hygiene: rename title-post to topic-title"