Added
- `zim.creator.Creator(language=)` can be specified as `List[str]`. `["eng", "fra"]`, `["eng"]`, `"eng,fra"`, "eng" are all valid values.
Changed
- Fixed `zim.providers.URLProvider` returning incomplete streams under certain circumstances (from https://github.com/openzim/kolibri/issues/40)
- Fixed `zim.creator.Creator` not supporting multiple values in for Language metadata, as required by the spec