[FIX] Vertical menu on flex-tab
# Conflicts:
#	packages/rocketchat-ui-master/public/icons.svg

Closes #7435

* Change all instances of Meteor.Collection for Mongo.Collection
http://stackoverflow.com/questions/25756664/is-it-mongo-collection-or-meteor-collection

* Include api.use(‘mongo’) where it was missing

* Fix message action button validation

closes 3305

Removed the cog button actions from showing up when the user is not in a room, this way people can't interact with the items when they're not in that room.

Fixes #3062