Relocate import in API (not as a feature anymore)?

[MoOx]

Since ﹫import integration is sort of a bonus feature (like its new friend postcss-url), maybe we should move that out of the features list.
Like minification (via compress option), I think we should have import and url, not with all features.

With #32, features will be enabled/disabled according to the browsers scope so it doesn't make sense to keep those features into the features list (yes this sentence is funny).

[magsout]

+1