Implement Bazel build

Change-Id: Ia0d8fa1b91ea4db94e0da951604aac02ffde8662

BUILD

diff --git a/BUILD b/BUILD
new file mode 100644
index 0000000..ffd3535
--- /dev/null
+++ b/BUILD
@@ -0,0 +1,11 @@
+load('//tools/bzl:plugin.bzl', 'gerrit_plugin')
+
+gerrit_plugin(
+  name = 'singleusergroup',
+  srcs = glob(['src/main/java/**/*.java']),
+  resources = glob(['src/main/resources/**/*']),
+  manifest_entries = [
+    'Gerrit-PluginName: singleusergroup',
+    'Gerrit-Module: com.googlesource.gerrit.plugins.singleusergroup.SingleUserGroup$Module',
+  ],
+)