Avoid writing build.json during a test.

allow empty messages in gRPC on windows

The test environment might be read only, so let's not modify a file just for running a test.

Updates the sample ObjC app to use protocol buffer messages

Creating nuget package for gRPC C#

Support update metadata callback function in php BaseStub

Generated with:
protoc --plugin=/usr/local/bin/protoc-gen-objc route_guide.proto
--proto_path=/Users/jcanizales/git/protobuf-objc/src/compiler
--proto_path=. --objc_out="./"

Fixes build problem in the ObjC sample client and adds local tests

On account of the change in the podspec structure.

Added JSON option for gRPC file loading

- Moves them to the root of the repo.
- Makes them pass lint (except for the release tag warning).
- Includes the script to rename time.h and string.h in the spec.
- Fixes the #includes in the wrapper files.

Adding a helpful warning message on top of the Makefile and BUILD file.