allow @imports in roole files
Roole support @import itself but before squashing block style files it should be resolved
But easier to import them by csspreprocessor provided by enb package
closes #6
drop 0.8 support and add 0.11 in `allow failure` mode
Merge pull request #8 from zxqfox/hotfix/resolve-import-in-roo-files

allow @imports in roole files