use brew install instead of easy_install in OSX (#4537)
use brew install instead of easy_install in OSX (#4537)

use brew instead of easy_install in OSX (easy_install keep failing for a month)
google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf,google/protobuf