Fix most specs. Includes:

* Remove unused minitests
* Fix unmaintained specs
* Only configure carriewave in appropriate environments
* Add shoulda- and paperclip- matchers
* Various other spec improvements
Accept pdf docs
GoogleDocumentProcessor -> DocumentProcessor
GoogleProcessor -> GoogleDriveProcessor
DocumentProcessor improvements. Includes:

* Refactor ProcessorFake to be enabled via a boolean config var
* Add DocumentProcessorDispatcher
* Create a NullProcessor for unknown files
* Add a pdf processor
* Make the DocumentProcessor use the DocumentProcessorDispatcher
Flesh out PDF interface and specs