Extract ::Configuration, ::Dataset, ::Metadata, and ::Search into different files.
Extracted HTTP request methods out to a separate file.
Added the ability to fetch favorites.
Streamlined Quandl::Dataset
Added Quandl::Favorites and Quandl request to the main lib file.
Abstracted data requests to a new Quandl::Request class, and removing unnecessary override param from Quandl::Request#initialize
Fixed request breaking + added multiset capabilities.
Updated version
Updated README with docs on Multisets and Favorites.