Revscoring

This release represents a major backwards incompatibility

Added
- Languages as feature sets.

Changed
- Codebase is now PEP8 compliant.

Fixed
- APIExtractor can't find language utilities

Changed
- Extended badwords and adds informal words for Persian language

Fixed
- Fixes pickling issue with languages (see 159)

Changed
- Synchronizes dependency versions with https://github.com/wiki-ai/ores and generalizes both.

Changed
- Improved installation instructions
- Selective language imports (no need to download all the dictionaries anymore)

Fixed
- Math domain error when processing imported revisions (`user.age`).
- Handle `RevisionDocumentNotFound` when scoring new pages