Refactored SleeperCell to handle more types of commands with better
static typing and layering.
Switched from JAXB to DOM Documents for Tandberg XML generation.
Added hangUp and isCallActive handlers for Tandberg and LifeSize.
Changed LifeSize dial string from x.y@z to z##x#y to support one-string
without screeching sounds.
Sleeper Cell starts blocking on AMQP after Spring is done initializing,
not during.
Added a few tests for dial string generation and Tandberg XML
generation.