The clock thread may not wake up during the daily pause
and daily resume minute, and when it does not, the corresponding
wall clock action will be missed.

The fix is in checkout the time of operations every time the
clock thread wakes up.

There is no longer need for the clock to wake up in the middle of
a wall clock minute.  So we improved the user experience by waking
up this thread at the beginning of every minute.

Use reason field in Broadcast to record reason for pause, cancel etc.

Improved reponse text to pause and resume commands.

in broadcast status message from CommEngine to portal.

rather than periodically on schedule.  This change has
no impact on user experience, and has improved logic,
and slight improvement in performance.

Also made all changes to the broadcasts structure under
synchronized control.

The common portion of the CommEngine properties file, are made
available to Broadcasts.

Broadcasts should determine their own service thread pool size.

Tested to work correctly with a 1-recipient SMS broadcast.
Need more testing.

to Portal.

dead_broadcast_viewing_period = 10
service_threadpool_size = 4
postback_threadpool_size = 3
postback_max_queue_size = 1999
postback_max_batch_size = 99