Link .ruby-version to a specific patch level matching heroku
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