Payment channels: mark a channel as inactive on the wallet side if the connected app dies.
Payment channels: basic unfinished activity that shows apps granted channel permissions and how much value they have left.

 Still lots of UI work left here. Also we need to make the model clearer.
Payment channels: Sample activity: disconnect from wallet in onStop to avoid leaking a service connection.
Payment channels: don't print exception stack traces on codepaths that are expected.
Payment channels: Sample activity: Don't prompt the user to reauth us until we actually used up all the granted quota.

The sample activity now tracks how much money it's spent in a preference, and when calling prepare() will only ask for however much is left. This is a simple "recharging policy" that is better than the default of asking the user to top us up every single time.
Payment channels: Thread safety fixes.
Catch up with latest bitcoinj API.