v0.1.8

• Added documentation compatible with cargo doc
• Added programmatic usage examples
• Moved jwt/mod.rs into jwt.rs (Rust 2018, path clarity)
• Exposing internal jwt submodule as public interface
• Renamed jwt::parse_token into jwt::parse
• Renamed all JWTDecode* enums into JWTParse* for consistency
• Updates dependencies to latest patch versions