face: Parametrizing DatagramFace to correct MulticastUdpFace logging

Change-Id: I8a117dd0209b3babe3b7df35cd692c268c059866
Refs: #1675
face: Switching to 2 sockets in MulticastUdpFace for sending and receiving

To send over UDP multicast, we should not bind to multicast address.
This is true at least on OSX 10.9, which generates "Can't assign
requested address" error (error code: 49).  However, without binding to
the multicast address, the socket may receive unnecessary unrelated
packets.  To solve this problem, this commit splits sending and
receiving into two sockets, one for sending and one for receiving.

Change-Id: Ibce05c7071fd683a26b3c88cd2a168546c5dc605
Refs: #1668
tools: Set broadcast strategy for HUB discovery prefix

Change-Id: Iaaf680e73be302b4068410e5c00260f3798b47fe
Refs: #1595