global replace health check proto v1alpha to v1

Fix SimultaneousReadWritesDone test

streaming API. In particular, Finish should not be called until the client
is sure that there is no more message to be read (as documented in
the comments for ClientStreamingInterface::Finish)

Expand gtest suites into individual run_tests tests

Support coreclr platform detection

Upmerge from 0.13

Fix PHP pecl package build on Mac

Updated travis to use Xcode 7.2 and SDK 9.2

clang-format all the things.

Fixing format and copyright.

That was overdue and the handshake is now slightly different for clients
(channels) and servers.

Added tests for code coverage

Fixes for gcc4.4

Optimize generate_projects

Coreclr compatible DefaultSslRootsOverride.cs

Injectable test credentials provider interface.

Timer->UsageTimer consistently

Remove outdated ref to openssl from Mac INSTALL instructions