Enabling cluster, sticky-sessions, level 4 based hash balancing

This enables the old cluster again, the problem described here:
https://community.nodebb.org/topic/3406/config-json-cluster-change

Will get fixed with this. The problem was that we can't rely on the ip anymore if any node component is behind a proxy. The fix enables hashing of values that are parsed from the header, after this it pushs the packet back to the read queue.

**Note:** I have reverted the cluster changes and the port thing, as I don't wanted to go get a deep dive into your code now. This pull request maybe more a template to build the whole thing. But you must decide yourself what to do ;)

For additional information see also:
https://github.com/indutny/sticky-session/pull/17
https://github.com/wzrdtales/sticky-session/blob/master/README.md


P.S.: The most things are just copy pasted from the work I've done on the sticky-sessions. This is a bit chaotic, but I have not the time today anymore to make it beatiful.