Upgrade bazlets to latest stable-2.16

- Avoid using deprecated depset union
- Automatically fix lint errors with buildifier
- Use target JDK for GWT compilation

Change-Id: I0c737e8969375562c57951fe177c0f50032a5ac4

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 6a4b338..2d78cf8 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "f7986f2d3e76ae0ca12a8c43ee91205725bd95e2",
+    commit = "86562a4c8c2e885aac89eafab34a90571be2ef09",
     #local_path = "/home/<user>/projects/bazlets",
 )