Features included in this merge:
- Added script to build and upload docker image for matrix test.
- Added script to create test cases and created go__master testcases based on it.
- Created dictionary for runtimes and gRPC releases for supported languages.
- Added go 1.7 and 1.8 Dockerfile/templates.

See tools/interop_matrix/README.md for details.

This reverts commit 79759fea, reversing
changes made to dc36f4df.

There is no reason why the client and server factories should be
implementations from the same base.
Doing the cleanup now so that implementation of the #10528 feature will
be less noisy.
Also, re-added tsi to clang-format which was dropped when moved from
src/core/lib to src/core.