* Update Bazel (to 3.4.1), gRPC, boringssl, absl.
* Always reinstall Bazel if needing to upgrade to a new Bazel version.
* Add patch for properly detecting Windows Python headers when building gRPC.
* Add minimum Bazel version check.
* Update docs with new Bazel version.
* Modifying WORKSPACE file, so that you can make the project used as a thirdparty
* Modifying WORKSPACE file, so that you can make the project used as a thirdparty
* add some files
* modify some repositories
* modify the name of 'ray_deps_build_all'
* Use buildifier as bazel script linter
* Checkout golang version in travis
* Using golang-1.8-go in travis
* Add golang apt-repository
* Fix the bazel lint failure example.
* Address comment
