StatsCompanionService sends messages to statsd

StatsCompanionService can now inform statsd that an alarm (for anomaly
alerting and for polling) has fired, so that statsd can act accordingly.

Test: manual created an alarm from statsd.main and checked logcat that
statsd received the broadcast that it fired
Change-Id: I1d33dfbee0d3e213c91dd6973d2622ecacc890c8