HTTP/2 Priority Algorithm Restructure

Motivation:
The current priority algorithm uses 2 different mechanisms to iterate the priority tree and send the results of the allocation.  The current algorithm also uses a two step phase where everything is traversed and allocation amounts are calculated and then everything is traversed again and everything that was allocated is sent.

Modifications:
- DefaultHttp2OutboundFlowController will allocate and send in the same looping structure.
- The recursive method will send only for the children instead of itself and its children which should simplify the recursion.

Result:
Hopefully simplified recursive algorithm with consistent tree iteration approach and 1 less iteration pass.
True.  I have been observing the profiler during the stress test and it performs similar (maybe a bit favorably compared to existing).  I can think about how to get rid of it (possibly go back to your global flag).