Updated zookeper resolver to new LB API

Update Header Field name rules

Adding apr to grpc-java Dockerfile

Introduced a registry for LB policies.

Enable additional warnings

Bring 0.11 into master

Fix mac build

Reintroduce DNS-based cases to dualstack_socket_test.c.

Fixing #3286

Added queries and fragments to uri parser

Put timeout on QPS test server shutdown

Enable servers to disable compression algorithms

Remove redundant docker files from grpc repo

Python Beta documentation

Fix Python docgen.

The old package directory handling was stale in grpcio's setup.py
command support module and docgen had a typo.

Make betaness explicit by setting Python version to 0.11.0b0.