Release 1.2.1

See the 1.2.1 milestone for the full list of related tickets and PRs.

Enhancements

1. Support for Laika site generation. #92 by @vshalts
2. Upgrade Paradox to version 0.2.12. #93, #101 by @sirthias & @jonas
3. Export optional environment variable map for Hugo. #98 by @bfritz
4. Update sbt to version 0.13.15 and fix warnings. #100 by @xuwei-k

Fixes

1. Fix issues with Hugo 0.20.1 version extraction. #96, #97 by @vshalts