Netty4 http mqm

Seems to work as expected on local stack, but could use some test cluster love. Summary of changes is:

- use netty4 instead of jetty for http backend for MQM. This solves some issues with limited thread pools and high query queue counts causing the ui to stop responding.

- some netty4 constructs used a bit outside the scope strictly needed for http handling. For instance, MQM now is part of the http netty pipeline -- it takes a query object and uses the pipeline as a consumer. The goal there being to simplify or at least make consistent the processing, threading, and error reporting logic in MQM.

- some near-future work will probably include some optimizations for string writing (writing to the pipeline for small character groups is pretty wasteful), removal/conversion of some query system specific interfaces / exceptions that can be simplified (mqm doesn't really need to be a 'query source' anymore), pipeline query ops and optimize concurrency settings for both them and the bundle-to-string sinks (they don't need to be run single threaded in many cases).