Refactor uploader and form_builder

This is the first step in resolving the outstanding bugs and fixes #104. It also simplifies the usage of content types to let it be completely backwards compatible.

Non-functional changes include removing a few autoloads (need to get rid of all of them eventually), pulled some of the uploader pieces into modules, and replaced all calls to class level configurations to their corresponding instance methods.  Calling the instance configuration methods defined by ```add_config``` lets the uploaders override the carrierwave_direct options -- which wasn't possible on an individual uploader level before.