fix(package): update convert-source-map to version 1.5.0

Closes #4

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "pre-commit": "~1.2.0"
   },
   "dependencies": {
-    "convert-source-map": "~1.3.0",
+    "convert-source-map": "~1.5.0",
     "css": "~2.2.1",
     "demolish": "1.0.x",
     "dollars": "0.0.x",