[JRO] Add rubocop.yml

Clean up a few things while working w/nested form branch
[JRO] Replace nested forms with form objects

accepts_nested_attributes for is a poor solution to the nested objects in forms problem so replacing that functionality, along with the nested_form gem, is a must.

* add app/forms directory and autoload it
* remove nested_form
* replace all instances of nested_form_for with form_for
* tighten up the permissions for strong params being used
* remove accepts_nested_attributes_for in the topic model
* add a NewTopic form object (this could probably be renamed to TopicForm?)