chore(package): update ember-source to version 3.1.0

Closes #241

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
     "ember-font-awesome": "^3.0.5",
     "ember-load-initializers": "^1.0.0",
     "ember-resolver": "^4.5.0",
-    "ember-source": "^2.13.0",
+    "ember-source": "^3.1.0",
     "loader.js": "^4.6.0",
     "normalize.css": "^7.0.0",
     "postcss-cssnext": "^3.0.2",