In progress: Fleshing out infrastructure to support multiple product types
General code restructuring.  Added main scraper methods for Kindle
Moved code from amazon_deets.rb to amazon_deets/general_merchanise.rb
Renamed general_merchanise.rb to general_merchandise.rb
Added default factory method for creating a scraper instance
Added ratings and reviews for Kindle books
Bumped version to 0.2.0
Updated README.md to demonstrate the new API