Hit remaining corner cases in httpcli/parser.c

 stop using _USE_32BIT_TIME_T and autodetect PlatformToolset on VS2015

Expand connectivity_state_test

Increasing json code coverage.

Remove pollset fd deletion path: its unused

Ruby auth metadata plugin

Add dns resolver test

Add tests for pipe usage

Fix memory leaks

Further coverage for compression

More C# coverage

Nuke unused code

Add iomgr socket_utils and sockaddr_utils tests

Slay dead code

add tests for public server apis

Cover more of workqueue

Add tests for thread options

Census tags propagation.

Cover ancillary frame error conditions

Make gpr_timespec platform agnostic.

PHP: metadata plugin based auth API

add test for lame client transport op

Get rid of SSL_CERT_FILE env entirely