This commit has the basics of notifications on Android working again, updated to the
latest Android SDK way of doing things (with channel IDs and grouping).
Android users will get notified when the app is open for new Peer Messages across all profiles.
In the future, this should be extended to add notifications for new peer invites, actual have actionable actions (accept/block)
and maybe even work when the app isn't open...
Sarah Jamie Lewis
Dan Ballard