[TACHYON-62] Netty

Netty implementation of the data server.

This patch is not done yet.  Its intent is to show the work I have right now for commenting.

This PR should not be merged until performance results come in.
"A mapped byte buffer and the file mapping that it represents remain valid until the buffer itself is garbage-collected."

http://docs.oracle.com/javase/7/docs/api/java/nio/MappedByteBuffer.html

So GC should free up the native space.