Bug 5740: Configure control-aware mailbox

Configured unit tests and production to use a control-aware mailbox
for Shard actors. The current code allows for a "shard-dispatcher"
to be defined so I added a section in the .conf that specifies the
mailbox-type appropriately (ie UnboundedDequeBasedControlAwareMailbox).

Change-Id: Ibdb404e1dfcc699471a8e899c491a09500ee04c0
Signed-off-by: Tom Pantelis <tompantelis@gmail.com>