Transforming gRPC.podspec to use build.json instead of globbing.

Various Jenkins-related tweaks.

-) created a .profile at the root of the docker image - seems the new nvm script requires that.
-) installing simplejson and mako python packages, for the sanity check.
-) calling prepare_travis.sh in order to try and download precompiled packages for openssl and protobuf.
-) using the new "config" axis.
-) improved the output of prepare_travis.sh.

Fixed file renaming in podspec template

Make warnings errors when building Python tests.

Update the Status API

Added flags support to grpc_op.

Add PHP timeout interop test

Fix NPE for trying to add metadata to error when it was nil

Make run_jenkins.sh actually fail on failure.

Add PHP to jenkins

only build unbroken tests in Windows run_tests.py

Remove failing globs from examples and tests

Simplify metadata usage

Revised the state machine.

Fix docs on gpr_slice_unref.

Fix docs on grpc_op_type.

include string_util.h for the prototype of gpr_strdup and fix a typo.