Implement dot in matching_metadata key for mongodb

Before the dict matching_metadata was stored as dict in mongo.
But mongo doesn't allow dot in dictionary key

This change converts the matching_metadata dict into a array like this:

[ { 'key': 'info.key.dotted', 'value': 'the_value'} ]

Fixes bug #1201886

Change-Id: Iab94c675749331ff7bfb0f74728dbd8f947f26f6
Merge "Implement dot in matching_metadata key for mongodb"