add keys to civicrm_entity_tag

Change-Id: Id57af4da8d37be18dbc2a0b2cfde4e98ab8853d1
Merge remote-tracking branch 'origin/master' into HEAD

* add keys to civicrm_entity_tag

Change-Id: I8ca0c637f015431240b2b70f1a1bbb6539478c7e