Merge branch 'handshake_api2' into http_connect

doc/images/load_balancing_design.png

doc/load-balancing.md

gRPC-Core.podspec

src/core/ext/client_config/channel_connectivity.c

...ore/ext/transport/chttp2/client/insecure/channel_create.c

...xt/transport/chttp2/client/secure/secure_channel_create.c

...core/ext/transport/chttp2/server/insecure/server_chttp2.c

...ext/transport/chttp2/server/secure/server_secure_chttp2.c

src/core/lib/channel/handshaker.c

src/core/lib/channel/handshaker.h

...e-c/tests/CoreCronetEnd2EndTests/CoreCronetEnd2EndTests.m

src/objective-c/tests/CoreCronetEnd2EndTests/Info.plist

src/objective-c/tests/Podfile

src/objective-c/tests/Tests.xcodeproj/project.pbxproj

...oj/xcshareddata/xcschemes/CoreCronetEnd2EndTests.xcscheme

src/php/ext/grpc/call.c

src/php/ext/grpc/call.h

src/php/ext/grpc/call_credentials.c

src/php/ext/grpc/call_credentials.h

src/php/ext/grpc/channel.c