Add Schemata::DEA::HelloMessage

Change-Id: Ie8180469934e070716d4e8e638c3678cc7e47349
Add Schemata::DEA::ExitMessage

Change-Id: I3bf2c713eacaa16a9f4299890c409aeba70fd552
Bump schemata versions

Change-Id: I7562f526408c3110191d12c6665cece2e51f7102
Change nats to pass json isntead of hash

Change-Id: I62c0c733fa8c4d398849667e99c80782594671c3
Add Schemata::DEA::HeartbeatResponse

Change-Id: Id137fb20e91bbab27bff064e554e0ddb72c3ee93
Change nats api to expect encoded strings

Change-Id: Ie573fbf0e15990766c92eea7da1ee32c460ce626