Remove redundant output encoding
Remove redundant output encoding

Encoding is no longer necessary thanks to
https://github.com/sass/node-sass/pull/729

michaellopez/broccoli-sass-source-maps,aexmachina/broccoli-sass-source-maps,davejachimiak/broccoli-sass,justinwoo/broccoli-sass-source-maps,k-fish/broccoli-sass,joliss/broccoli-sass