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.

log4j-2 causes problems because
1.  WE use Configurator to configure from a properties file.
2.  Other dependency uses log4j-1, improper to mix versions.
Symptoms include
. No logging
. Failure to load Logger class.

state.

This reverts commit 538dede739.

Also fix bug of not doing CANCEL properly.

various states.  Delay closing HttpClient until all postback threads have
exited.

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