Restart on failure as well as "success", since cjdns shouldn't stop

CJDNS has stopped on it's own twice in the past couple of months, and the connection stayed down until I restarted it manually both times, despite having systemd watching the process, because the failure causes it to finish with a **successful** exit status. Considering CJDNS shouldn't be stopping without instruction to do so either way, I thought it was appropriate to modify the systemd service so that it will restart cjdns whenever it stops, regardless of the exit status.

Cheers!