Merge github.com:grpc/grpc into credit

Makefile

build.json

include/grpc/support/histogram.h

src/compiler/python_plugin.cc

src/core/iomgr/resolve_address_posix.c

src/core/support/histogram.c

src/core/surface/call.c

src/node/binding.gyp

src/node/ext/byte_buffer.cc

src/node/ext/call.cc

src/node/ext/call.h

src/node/ext/channel.cc

src/node/ext/channel.h

src/node/ext/credentials.cc

src/node/ext/credentials.h

src/node/ext/node_grpc.cc

src/node/ext/server.cc

src/node/ext/server.h

src/node/ext/server_credentials.cc

src/node/ext/server_credentials.h