Fix datagram destination to use the host/port provided to DefaultSocketProvider

- Use default constructor for DatagramSocket. Previously the host/port were
  passed to DatagramSocket to be used as the locally-bound address.
- Set the destination host/port in the DatagramPacket constructor. Previously
  the DatagramPacket was being constructed with no destination.
- Add import of java.net.InetAddress, remove import of java.net.InetSocketAddress.

http://docs.oracle.com/javase/6/docs/api/java/net/DatagramSocket.html#DatagramSocket()
http://docs.oracle.com/javase/6/docs/api/java/net/DatagramPacket.html#DatagramPacket(byte[], int, java.net.InetAddress, int)