server: Handle broadcast intent and receiver

Ensure the receivers of broadcast intent is not launched before boot
completion by adding an intent flag, since connectivity events can
happen before boot has completed.

Change-Id: Id6fc9e34c89d947d768def38e5c5bb0df54a3a7b
Release wakelocks acquired by SyncManager

Release the wakelocks internally acquired by SyncManager to improve
power performance.

Change-Id: I6d9663292cb4471d92ed9132beb7ed1ba2e8128f
CRs-Fixed: 585825