[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.
Yep,I concur but this style is happening everywhere in Tachyon so keeping it consistent until new code style is implemented. 
I think it was somehow following Google Java style that give an opening of interpretation to have final as constants which requires to use all upper case.