Merge branch 'master' of github.com:grpc/grpc into make-ruby-installable

test/distrib/csharp/.gitignore

test/distrib/csharp/DistribTest.sln

test/distrib/csharp/DistribTest/.gitignore

test/distrib/csharp/DistribTest/App.config

test/distrib/csharp/DistribTest/DistribTest.csproj

test/distrib/csharp/DistribTest/Program.cs

test/distrib/csharp/DistribTest/Properties/AssemblyInfo.cs

test/distrib/csharp/DistribTest/packages.config

test/distrib/csharp/NuGet.Config

test/distrib/csharp/build_vs2015.bat

test/distrib/csharp/run_distrib_test.sh

test/distrib/csharp/update_version.sh

tools/dockerfile/distribtest/csharp_jessie_x64/Dockerfile

tools/dockerfile/distribtest/csharp_jessie_x86/Dockerfile

tools/dockerfile/distribtest/csharp_wheezy_x64/Dockerfile

tools/jenkins/build_and_run_docker.sh

tools/jenkins/docker_run.sh

tools/run_tests/distribtest_targets.py

tools/run_tests/task_runner.py