PostDrops: Fix for drops with any metadata item null

* A list of drops that had a drop with either tags, places, links or
media null was causing an ArrayIndexOutOfBounds exception due to the
'i' variable not updating correctly thus an incorrect index created.
* Solution is to use a for loop instead of foreach to ensure that both
i and j counters always increase when a 'continue' statement is
encountered.
PostDrops: Fix rivers_droplets sequence

* Sequence was not updating after inserting drops because
dropRiverList.size was being read before the list was initialized.
PostDrops: Update river max_drop_id and drop_count

* Update the rivers table with these values when inserting into
rivers_droplets
RiverChannels: Send notificaiton to MQ on update

* Added Spring AMQP
* Send a notificaiton on channel add, delete or modify.
Added MockAmqpTemplate

This allow integration testing without a real broker running.
Fix routing key for mq channel notifications

Was hard coded to rss instead of channel name from the updated channel.