Retrieve list of factories from home

 * HTTP#get and #post return Http object
 * Rename Http#json to #to_hash
 * Adds #response_json attr_reader
 * Removes RemoteFactoryGirl#params
 * Don't memoize http requests for Http#get and Http#post
 * Refactory RemoteFactoryGirl#initialize interface
    Pass factory name, and attributes into
    RemoteFactoryGirl#create instead of
    RemoteFactoryGirl#initialize because
    RemoteFactoryGirl#factories does not have/need a factory
    name or attributes.
Check if configured in Http#initializer

Check for configuration in initializer rather than checking in #get and
#post