Agent - Add AXFR Capability

*When a NOTIFY comes in and verifed an AXFR is triggered
*Adds a concept of Masters, separate from "allow_notify"

Change-Id: Ia7d70561cdae73c7cca956f821fc3b11736b087c
Agent - Add Support for Receiving Unassigned OPCODEs

*Agent parses message with OPCODEs 6 and 7 and calls
for a create and delete event, respectively.
*There isn't much done at the moment, but they will call into
the pluggable backend when implemented.

Change-Id: I48c2deb729c853bebec74a04b6c97c89426000c1