Release new major version because the previous release was a breaking change in certain scenarios
See: https://github.com/webpack-contrib/sass-loader/pull/250#issuecomment-228663059
The new algorithm is aligned to libsass' way of resolving files. This yields to different results if two files with the same path and filename but with different extensions are present. Though this change should be no problem for most users, we must flag it as breaking change. #135#138