Changes:
- Enhance the windows installer (fixes #638)
- Update autoprefix to v7.1.6
- Update clean-css to v4.1.9
- Update coffee-script to v1.12.7
- Update postcss to v6.0.14
- Update uglify-js to v3.1.9
- Update uglify-es to v3.1.9
- Update sass to v3.5.2 (fixes #697)
- Replace setting GEM_HOME and GEM_PATH with Gem.paths. (fixes #679)
- Add support for distinguishing UglifyJS errors from bugs. (fixes #645)
- Add Polish language. (Thanks to @djmassive) (#693)
- Fix French translation. (Thanks to @NumEricR) (#485, #486)
- Add Persian language. (Thanks to @mw2017) (#494)
- Add Korean language. (Thanks to @k22pr) (#660)