Updated the arguments for the get_title_versions method.
Added test names for the OpenSubtitle's IProvider interface methods (No
implementation yet).
Added tests implementation for the download_subtitle_buffer of OpenSubtitle's provider.
Some small changes to the requestsmanager methods api.
Add tests names for the new optional response_headers paramters for the requestsmanager.
Changes the response_headers parameters type from dict to list.
Added tests implementation for the requestsmanager new reaponse_header parameter.
Finished implementation of the response_header parameter in the requestsmanager.