Refactor and move get_history_file_list() to Instance model.
Finish refactoring download_history_files().
Remove get_histories(), get_history(), get_history_contents(), get_history_content(), get_history_file_type() and get_complete_histories()
Remove get_libraries(), get_library_id(), get_library_item_id(), get_library(), get_library_contents(), get_library_content(), put_into_library() and get_complete_libraries()
Remove get_workflows() and get_workflow_id()
Remove galaxy_connector.connection