This adds namespace lookup to serializer_for (#1968)

* This adds namespace lookup to serializer_for

* address rubocop issue

* address @bf4's feedback

* add docs

* update docs, add more tests

* apparently rails master doesn't have before filter

* try to address serializer cache issue between tests

* update cache for serializer lookup to include namespace in the key, and fix the tests for explicit namespace

* update docs, and use better cache key creation method

* update docs [ci skip]

* update docs [ci skip]

* add to changelog [ci skip]

.travis.yml

@@ -20,7 +20,8 @@ cache:
 
 script:
   - bundle exec rake ci
-
+after_success:
+  - codeclimate-test-reporter
 env:
   global:
     - "JRUBY_OPTS='--dev -J-Xmx1024M --debug'"