OR-443 add specific middleware for adding attendees route
OR-443 update PUT /api/conferences/cid/attendees/uid to allow adding participants if not conf admin
OR-443 add tests for canAddAttendee middleware
OR-443 add midway tests for PUT /api/conferences/:cid/attendes/:uid
Merge pull request #494 in OR/rse from OR/rse-gcrosmarie:OR-443 to master

* commit '5295cb7464d3be21d6f5ed066d71df8ff84112da':
  OR-443 add midway tests for PUT /api/conferences/:cid/attendes/:uid
  OR-443 add tests for canAddAttendee middleware
  OR-443 update PUT /api/conferences/cid/attendees/uid to allow adding participants if not conf admin
  OR-443 add specific middleware for adding attendees route