Bump to Bazel 2.0.0 and add support for an RBE

Bazel 2 is very shiny, and so must be used. The support for a Remote
Build Environment makes life a little bit easier if one is
available. Hopefully at some point soon we can get access to the
Google RBE alpha....

WORKSPACE

@@ -8,6 +8,20 @@ workspace(
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
+http_archive(
+    name = "bazel_toolchains",
+    sha256 = "e2126599d29f2028e6b267eba273dcc8e7f4a35ff323e9600cf42fb03875b7c6",
+    strip_prefix = "bazel-toolchains-2.0.0",
+    urls = [
+        "https://github.com/bazelbuild/bazel-toolchains/releases/download/2.0.0/bazel-toolchains-2.0.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-toolchains/archive/2.0.0.tar.gz",
+    ],
+)
+
+load("@bazel_toolchains//rules:rbe_repo.bzl", "rbe_autoconfig")
+
+rbe_autoconfig(name = "rbe_default")
+
 http_archive(
     name = "rules_jvm_external",
     sha256 = "e246373de2353f3d34d35814947aa8b7d0dd1a58c2f7a6c41cfeaff3007c2d14",