fix(package): update sass-graph to version 3.0.4

Closes #16

Author: greenkeeper[bot]

package.json

@@ -29,7 +29,7 @@
     "event-stream": "3.3.4",
     "gulp-util": "^3.0.8",
     "lodash": "^4.17.4",
-    "sass-graph": "^2.2.3",
+    "sass-graph": "^3.0.4",
     "through2": "^2.0.3",
     "vinyl-fs": "^3.0.0"
   },