Implement Bazel build

TEST PLAN:
  $ bazel test gitiles-servlet/...

Run debug version:
  $ sh {path/to/src}/tools/run_bazel_dev.sh

TODO:

 * publishing maven artifacts.
 * check out Bazel's generate_workspace.
 * intellij/eclipse project generation

Change-Id: I288011ce622536ce72c59a1961f962db9fe9e761

lib/junit/BUILD

diff --git a/lib/junit/BUILD b/lib/junit/BUILD
new file mode 100644
index 0000000..c2a6fcc
--- /dev/null
+++ b/lib/junit/BUILD
@@ -0,0 +1,13 @@
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+java_library(
+    name = "junit",
+    exports = ["@junit//jar"],
+)
+
+java_library(
+    name = "hamcrest-core",
+    exports = ["@hamcrest_core//jar"],
+)