Add bazel rule to run buildifier; fix up formatting problems in bazel files

Change-Id: Ifa8ab12ed564fa2eaf5edd781281aa5cae52d17a
diff --git a/BUILD b/BUILD
index 16f97da..16ee973 100644
--- a/BUILD
+++ b/BUILD
@@ -94,3 +94,15 @@
     output_to_bindir = True,
     visibility = ["//visibility:public"],
 )
+
+load("@com_github_bazelbuild_buildtools//buildifier:def.bzl", "buildifier")
+
+buildifier(
+    name = "buildifier_check",
+    mode = "check",
+)
+
+buildifier(
+    name = "buildifier_fix",
+    mode = "fix",
+)