* Shown next to subject (non-final layout)
* Value taken from provider data
* Tapping star toggles state
* State writes back to provider
NOTE: I am currently doing the provider writeback via direct provider
calls (using the synced-message URI) but not doing it with a service call,
so at this point there is no triggering of any server-side update.
However a sync engine might "discover" the change.
NOTE: I made a global change of "mMessage" to "mOldMessage" because
there is still a lot of legacy code in MessageView and I wanted to clearly
demarcate the code that still needs to be redone.
