Openergy

* m: iter_unitcleaners and iter_importer_series added
* p: empty values of excel unitcleaners are now managed properly

* (m) pandas requirements were loosened

* (p): multiclean_config_model.xlsx added to MANIFEST.in

* (m): platform_to_excel added
* (M): cleaner batch_configure renamed to excel_to_platform
* (M): importer client kwarg removed
* (m): requests list_iter_all added
* (m): client management changed
* (m): util get_series_info added

* (m): list_iter_series created
* (M): first official release

* (m): client simplified
* (m): get_series_info added to api