Moved getOwnWlanIpAddress to utility, in preparation for using it in the name server code.
Name server will now use getOwnWlanIpAddress instead of getOwnIpAddress, since we will no longer be running it on cedar.
NameServer: Restored support for cedar. It will now detect if running on a DNS-findable host. If so, use the results of the DNS lookup. Otherwise, use the wlan0 address.
WifiCommunicator: Use Wlan address instead of DNS-provided ip address (which was using localhost). Also, cleaned up handling of received packets - they were getting returned as Packets instead of UDPPackets, which was nonsensical since the ListeningSocket assumes that it is receiving UDPPackets. Changed WifiCommunicator to reflect this - it simplified the code in BigBuckSensingNode somewhat.