Divij/client message flow

Wiring up application registration with client "init_interview" message.

For the time being we are hardcoding registered applications see line 52, 53 on interview.py. Registration via selection screen to follow.

PEP8 Compliant. Tested notes and heartbeat application.
I know I added this here, but we don't need it since I removed the gen.Task calls. Remove it from here and we can add it back if we end up using gen.Task calls again