Add ZBeacon implementation
Fix checkstyle errors
Merge pull request #211 from c-rack/master

Add ZBeacon implementation
Problem: beacon messages are not always filtered out for local addresses

Solution: Use different technique for checking whether the sender
address is local.
Problem: current ZBeacon tests are not testing whether messages are
received.

Solution: Add CountDownLatch to ZBeaconTest in order to actually check
whether the beacon message was received or no.
Merge pull request #212 from ifesdjeen/improvement/zbeacon-localhost-and-test

Problem: beacon messages are not always filtered out for local addresses
Merge pull request #213 from ifesdjeen/improvement/zbeacon-tests

Problem: beacon messages are not always filtered out for local addresses
Merge pull request #214 from trevorbernard/master

Remove guava as a dependency