ASACORE-835 Fix ping from service to client
	    in session.

If an app makes a Ping to a remote app, the routing node will perform
a DBus ping to the remote app if a session exists.

Also, do not allow more than one ping in progress for local apps.

Change-Id: I8af75cd0b0796cd8eaf6173c7f7cbeb45df5aba5
Signed-off-by: Sheshambika Venkateshwaran <sheshamb@qce.qualcomm.com>
Merge "ASACORE-835 Fix ping from service to client 	    in session." into RB14.12