[0.4.0] Mime type application/octet-stream returned for .dieter manifest in dev mode

First off, thank you for sharing dieter! I am new to clojure, and for my first compojure project I have been trying to integrate dieter 0.4.0. I have a `site.css.dieter` file that always returns mime-type `application/octet-stream` in development mode. But, it works correctly in production mode, returning `text/css`. 

I noticed an extra [`wrap-file-info`](https://github.com/edgecase/dieter/blob/master/dieter-core/src/dieter/core.clj#L75) that may have been introduced in a bad merge commit? 
https://github.com/edgecase/dieter/commit/b018f86fb0ff09f2fc99b9c1949a6ff736695ef1

Hope this helps!