Refactor test folder and create dummy app (#287)

* try to move dummy application into spec
* travis cleanup
* rubocop cleanup

lib/impressionist/counter_cache.rb

@@ -48,8 +48,11 @@ module Impressionist
       end
 
       def counter_caching?
-        impressionable_class.
-          impressionist_counter_caching?
+        if impressionable_class.respond_to?(:impressionist_counter_caching?)
+          impressionable_class.impressionist_counter_caching?
+        else
+          false
+        end
       end