Make bazel build fully hermetic

We no longer reference @bazel_tools//third_party. All of our transitive
dependencies are now specified explicitly in our WORKSPACE file.

I also fixed the way that jar dependencies are exported, so we don't
break strict dependency checking.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=116421176

third_party/java/jetty/v6_1_22/BUILD

@@ -8,6 +8,6 @@ java_library(
     exports = [
         "@jetty//jar",
         "@jetty_util//jar",
-        "@servlet_api//jar",
     ],
+    runtime_deps = ["@servlet_api//jar"],
 )