cvss 0.2.0

Common Vulnerability Scoring System parser/serializer
Documentation 
## [0.2.0] (2019-08-28)

- Add `Base::exploitability` and `impact` methods; docs ([#5])
- `serde` support ([#4])

## [0.1.0] (2019-08-27)

- Initial release

[0.2.0]: https://github.com/RustSec/cvss.rs/pull/6
[#5]: https://github.com/RustSec/cvss.rs/pull/5
[#4]: https://github.com/RustSec/cvss.rs/pull/4
[0.1.0]: https://github.com/RustSec/cvss.rs/pull/2