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

Improved reponse text to pause and resume commands.

The service threads do not terminate immediately, but, instead
each service thread picks up one more job before terminating,
causing servicing more jobs which are not reported back to portal.

This happens when all remaining jobs are being serviced by
service threads when PAUSE is initiated.  Similarly fixed
for CANCEL.

before progressing to COMPLETED state and issue state change
notification to portal.

Also make state change report to be a single line for ease
of grep'ing log file.

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.

Broadcast state ALLDONE added to mark the event of completing postback,
and when all threads are to be terminated.

CommEngine report of a broadcast adds service times,
and number of transactions.

Broadcasts should determine their own service thread pool size.

This would lead to memory leak when SMSEngine is shutdown.

returning 422 HTTP status to indicate message is spammed.

state.