[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.
`ServerSocketChannel.open()` may throw `IOException` which cause `Selector` never be closed and causes the file descriptor leak. I think `socketSelector.close()` need to be called in finally block