Merge remote-tracking branch 'upstream/master' into handshake_api

.travis.yml

composer.json

examples/objective-c/auth_sample/AuthTestService.podspec

examples/objective-c/auth_sample/Podfile

examples/objective-c/helloworld/HelloWorld.podspec

examples/objective-c/helloworld/Podfile

examples/objective-c/route_guide/Podfile

examples/objective-c/route_guide/RouteGuide.podspec

examples/php/README.md

examples/php/composer.json

gRPC.podspec

include/grpc++/support/slice.h

package.xml

setup.py

src/compiler/config.h

src/compiler/cpp_generator.cc

src/compiler/cpp_plugin.cc

src/compiler/csharp_generator.cc

src/compiler/csharp_generator_helpers.h

src/compiler/csharp_plugin.cc