Add ddp connection status to agent info table

[paulgration]

A Galicaster can appear 'online', because images are being received from it (screenshot of galicaster interface, camera view, presentation view) which updates the heartbeat and does confirm that galicaster is on and running but it doesn't mean that the DDP connection is alive. If for example the password in mongodb for the galicaster user doesn't match the one used for nginx (for image posting from galicaster) and the galicaster DDP configuration credentials, then the Galicaster will appear online but interaction with it is limited/misleading (VU doesn't update, starting recording remotely from within peakaboo will appear as if it is starting a recording but won't be). It would be good to add information to the capture agent info table to display it's DDP connection status, and perhaps add some indicator on the room list view.