If getContext() == null, don't return API results.

This handles memory pressure automatically.

Also, move serializable up the inheritance chain.
The log tag should be canvas-api
Merge pull request #3 from joshruesch/master

If getContext() == null, don't return API results.

Also adds in an API for marking conversations as unread as well as adds a 'NoNetwork' method to APIStatusDelegate.

This also fixes a crash regarding Masquerading.