chore(package): update rollup-plugin-commonjs to version 9.1.0

Closes #274

Author: greenkeeper[bot]

package.json

@@ -77,7 +77,7 @@
     "rimraf": "^2.6.2",
     "rollup": "^0.52.0",
     "rollup-plugin-buble": "^0.18.0",
-    "rollup-plugin-commonjs": "^8.2.1",
+    "rollup-plugin-commonjs": "^9.1.0",
     "rollup-plugin-node-resolve": "^3.0.0",
     "rollup-plugin-replace": "^2.0.0",
     "rollup-plugin-scss": "^0.4.0",