Wercker's Docker stack is broken and useless

wercker.yml

@@ -1,7 +1,14 @@
-box: ruby
+box: wercker/rvm
 build:
   steps:
+    - rvm-use:
+        version: 2.2.3
+    - script:
+        name: update bundler
+        code: gem update bundler
+
     - bundle-install
+
     - script:
         name: clone hamlit1
         code: bin/clone
@@ -23,6 +30,3 @@ build:
     - script:
         name: "[benchmark] basic bench by slim"
         code: bin/bench bench benchmark/etc/slim_bench.haml
-    - script:
-      name: minitest
-      code: bundle exec rake test