avro

AVRO-1973: Upgrade netty to the latest 3.x release

Upgrading netty version to 3.10.6 caused a test failure. The root cause was
that from 3.6.0 netty does not interrupt worker threads therefore,
server2.close() would hang until blockingSimpleImpl.releaseRunPermit() is
invoked. Could not find any way to call an interrupt on the related workers
therefore, modified the test.

Signed-off-by: Ben McCann <ben@connectifier.com>
Signed-off-by: Sean Busbey <busbey@apache.org>

Closes #178