If the group's owner is spamming, unsubscribe.

This keeps the visual language consistent: rating icon plus name equals
author.

Returning null from getItem() was causing too many problems, and the
item was triggering onItemSelected() before the other items had been
loaded.

(Although it isn't possible to create an identity yet...)

The invitation and private messaging UIs are currently broken. Some key
rotation bugs were fixed; others may have been created (unit tests
needed). An encoding for private keys was added. Pseudonyms were moved
out of the messaging package and ratings were moved in.