Add support for Bazel in Gerrit tree build

Change-Id: I544075b792e27dc9c32451f95f6f0d7c7109d62c

BUILD

diff --git a/BUILD b/BUILD
new file mode 100644
index 0000000..990ccaf
--- /dev/null
+++ b/BUILD
@@ -0,0 +1,10 @@
+load("//tools/bzl:plugin.bzl", "gerrit_plugin")
+
+gerrit_plugin(
+    name = "avatars-gravatar",
+    srcs = glob(["src/main/java/**/*.java"]),
+    resources = glob(["src/main/resources/**/*"]),
+    manifest_entries = [
+        "Gerrit-PluginName: avatars-gravatar",
+    ],
+)