starting tests for the preview method default options
using OpenStruct to wrap options and setting up default caching system
define fetch method on preview class #55
create test for fetch method in engine_spec
refine and make fetch test pass for if cache exists
create fetch test for when cache key doesn't exist
edit description for cache expiration test
change extracted data to return empty hash in engine spec
require and use moneta for cache #55
make cache default options into a singleton method to dry code #55
change has_key? to key? in spec to use moneta method
switch to caching extracted data instead of entire html response #55
re-evaluating tests for checking cache
add tests for cache storage and expired cache replacement #55
start refactoring preview and engine modules b/c logic not using cache #55
refactor amazon onebox - data method #55
refactor opengraph module - raw method #55
refactor oneboxes - change @body to raw in extracted_data method #55