Factor out the pollset kicking mechanism and eliminate sharding

This change pulls out a separate pollset_kick module, which currently
uses a freelist of pipes dynamically assigned to pollsets when they
enter polling rather than the previous racy sharding mechanism.

We ultimately may wish to eliminate the dynamic assignment for multipoll
sets, but this should be sufficient for the moment.

clang compile fixes

Allow running PHP unit tests from run_tests.py

Add an optional server shutdown event.

Adding a few more comments in the Makefile template

Fixes a regression in the style pull request

Grpc ruby add rubocop fix lint style issues

Allows servers to expedite shutdown once all in-progress calls are
completed. We may want to eventually remove grpc_server_shutdown in
preference to this.

Fix returned status

The client should return status deadline exceeded when the deadline is
exceeded (not cancelled status)

Node generated code

Compile fix

- add rubocop as a dev dependency
- fixed many style violations it reported, often using --auto-correct
- add a rubocop config
 - .rubocop.yml shows the exceptions
 - .rubocopy_todo.yml tracks outstanding style issues
- adds a rake task to allow rubocop styling checks to be automated

Fix run_test.py so it runs the first time

Changing size type in Transport Security (TSI) from uint32_t to size_t

Will remove grpc impedance mismatch.