workspace: add buildifier

To run: `bazel run //:buildifier`

To be done: document and automate

Change-Id: I7631e45915d61d2b95b0d8b0d893d0e1de2ccbed
Reviewed-on: https://gerrit.hackerspace.pl/c/hscloud/+/1847
Reviewed-by: palid <palid@hackerspace.pl>
diff --git a/BUILD b/BUILD
index 69fd218..779af8e 100644
--- a/BUILD
+++ b/BUILD
@@ -27,3 +27,8 @@
     constraint_values = ["@bazel_tools//platforms:linux"],
     visibility = ["//visibility:public"],
 )
+
+load("@com_github_bazelbuild_buildtools//buildifier:def.bzl", "buildifier")
+buildifier(
+    name = "buildifier",
+)