Updated MainActivity.java
Override onStart() to start background threads and onStop() to interrupt
background thread.
Updated UdpBroadcaster.java
Extracted some local variables as static constant.
Now send emtpy data rather than needlessly local ip address.
Changed exception catch to allow better control and report.
Now sleep for 1 second between broadcasts.
Updated UdpBroadcaster.java
Correctly close UDP Socket after sending broadcast.
Correctly break away from while-loop when interrupted during thread
sleep.
Updated UdpClient.java
Stop using wildcard address, call the right constructor for
DatagramSocket instead.
Now calls instance of TcpSender and passes IP address of broadcasters.
Correctly closes UDP Socket.
Stop converting packet data to String, get IP of broadcaster through
getPacket.getAddress() instead.
Implements better exception catching mechanism.
Merge pull request #15 from shunghsiyu/udp_fix

Fix UdpBroadcaster and UdpClient