Extract task of retrieving movie info form different sources to separate
modules/classes.
Big refactoring of Aggregator class, extracted functionality into
appropriate class/modules.
Separate module for each movie source, with specific classes for each
result type (poster, basic info, rating etc).
Improved handling when RottenTomatoes API returns insufficient data.
Trimmed Aggregator class completely down.
Moved aggregator spec to integration folder since it is more suitable
there.