[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.
True, `header.writeShort(DataServerMessage.DATA_SERVER_RESPONSE_MESSAGE);`

Can I fix this in the remote write patch?  Will need to change a few things, so can make this cleaner there.