ASACORE-917: new signal delivery mechanism

This is an alternate approach for the signal delivery problem.
I've defined a special SessionId value SESSION_ID_ALL_HOSTED. If you use
this session id in the BusObject::Signal call, the signal will be
emitted in each session hosted by the emitter.

Change-Id: I3ff643992730c53c33ae2b5b707e718105db143d
Signed-off-by: Meggan Ehret <meggan@qeo.org>