Changes:
1. Remove stuff no longer needed. Lots of the heavy lifting were there
because we were running our own jenkins cluster and had to manage all
the test logs ourselves. Now they are useless.
2. Change "-j2" to "-j4" to speed up the test a little bit. Kokoro
machines have 4 logic CPUs according to their spec.

1. Added C++ tests under the release docker image.
2. Cleaned up tests.sh and removed traivis stuff.

1. Added C++ tests under the release docker image.
2. Fixed a compile issue with the docker image.
3. Cleaned up tests.sh and removed traivis stuff.

Add googletest as a submodule in third_party/googletest.

The last up-integration from github to google3 was made at commit
e28286fa but somehow the change in
that commit is not actually in the up-integration CL and as a result
that change was reverted by the down-integration. Restoring them
should make the jenkins tests running again.

When it runs in parallel with other jenkins tests, multiple tests start
to fail probably because cpp_distcheck will update the C++ lib that
other tests (such as python_cpp) are depending on.

Change-Id: Ibca0243084bb6b81c811b62c75288e20cc2aabf5

These tests are already covered by jenkins and right now jenkins can
finish these tests much quicker then travis.

Change-Id: I5799761ccc338211d750940e3cf4c8e2569c8144

1. Added ruby22 and jruby tests to jenkins.
2. Added javascript tests to jenkins.
3. Added golang tests to jenkins.
4. Removed ruby19/ruby20 tests from travis. Support for ruby 2.0 has
   ended since 2016/02/24.
   https://www.ruby-lang.org/en/news/2016/02/24/support-plan-of-ruby-2-0-0-and-2-1/

Change-Id: Ie984b06772335352a4be7067ab2485f923875685