* Add some imports that make it easier to build with Bazel
* Use "/tmp" paths for sockets in tests
* Move `asio_test` into `run_gcs_tests.sh` instead of starting and stopping Redis within the test fixture with a `system` call.
* Enable --scoped-enums in flatbuffer compiler.
* Change enum to c++11 style (enum class).
* Resolve conflicts.
* Solve building failure when RAY_USE_NEW_GCS=on and remove ERROR_INDEX suffix.
* Merge with master and fix CI failure.
