Add the PATCH method for the monitoring API

Since the specification release, a new API has been added to the
monitoring interface. Which is an acknowledged operation for the
alarm event.

This commit will support SMO requests the O2IMS API to
acknowledge and clear the alarm event.

Test Plan:
1. Request the API to acknowledge the alarm.
2. After ack the alarm, it was requested the stx clear
   its alarm.

Issue-ID: INF-449

Change-Id: Ic2cb07cbc0784793d1b1de637b7c8a6c29d3f6a2
Signed-off-by: Zhang Rong(Jon) <rong.zhang@windriver.com>