Remove resource users from reclaimer lists when shutting down

Otherwise, a null closure could be executed to reclaim, the reclaimation
finished edge would never be executed, and a future allocation will
stall forever.

Deflaked lb_policies_test

Pin bazel version to 0.4.1 release tag

Script for pushing pre-built testing docker images to dockerhub.

Fix logic race in chttp2 write path

PHP Unit test changes

Add configurable exit grace periods and shutdown handlers

1. In the State change test, 123->0 will hit a c-core GPR_ASSERT if
debugging is enabled because 123 doesn't map to a state that can
be printed.
2. In the Server test, 8888 is sometimes unavailable, so we just use
a wildcard port.

The server cleanup method is untested.

The join() function that exposes it is only called by the internals of threading.py, and we don't hold a reference to the server thread to explicitly join() it, and I'm not sure we should add a reference just for this purpose.

Moreover, the threading.py only calls join(None), the code path in question isn't even exercised by the internals of threading.py. Its just there to make sure we properly follow the join(timeout) semantics.

C# cleanup package building

Fix a memory leak in grpc_udp_server_add_port()

Capture name change of CocoaPods generated target

Deflake grpclb test

Propagate (some) signals to subprocesses in json_run_localhost

Fix TCP shutdown path on Windows

Break infinite connection retry loop

Previously, we'd keep retrying a connection until the channel closed.
With this change, we only retry connecting *if there's a watcher on the
subchannel connection state*. This ultimately means that if the
lb_policy doesn't care if the subchannel connects, it'll stop trying.

Basic config for internal CI (take 2)

Draft of C# server reflection