Merge branch 'stable-3.1'

* stable-3.1:
  Upgrade bazlets to latest stable-3.1 to build with 3.1.7 API
  Upgrade bazlets to latest stable-3.0 to build with 3.0.11 API
  Remove the commented-out snapshot plugin api lines
  Adapt SNAPSHOT plugin api example to the 3.1 version
  Upgrade bazlets to latest stable-3.1
  Prepare for new gerrit_api snapshot version usage
  Upgrade bazlets to latest stable-3.0
  Upgrade bazlets to latest stable-3.0

Change-Id: Ief6f46ac07263f719f294807c3473f3607c87750

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 1c2385f..c528929 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 load("//:bazlets.bzl", "load_bazlets")
 
 load_bazlets(
-    commit = "b6cb89690a5e06261932eb30c95fd8db34a7943a",
+    commit = "53cfe52b1b691040fd03dfe025c0a381df48c6ee",
     #local_path = "/home/<user>/projects/bazlets",
 )