Plugin stylesheets were already allowed to be auto-imported from the assets/stylesheets/plugins directory.

Plugin stylesheets were already allowed to be auto-imported from the assets/stylesheets/plugins directory.
Please see this commit: imathis/octopress@9364f37ac75a028c7ce12de06cc00da5bc2506b9

And I moved the file `_ribbonp.scss` from `sass/custom/` to `sass/plugins/`.

Thanks for contribute, I like your plugin. =)