Is custom importer option really needed considering there is already includePaths?

[ivanblazevic]

@LakMoore just wanted to quick check - have you ever used custom importer, just wondering was it working for you because configuration is in json and for importer we need to provide JS function? Reason for asking is because I am upgrading sass lib and importer now has different structure so I would also like to cover it with e2e tests but first wanted to check if that feature is really required because there is already includePaths option which is alternative for importer.

Originally posted by @ivanblazevic in #2 (comment)