chore(package): update rollup to version 0.60.2

Closes #4

Author: greenkeeper[bot]

package.json

@@ -20,7 +20,7 @@
     "chokidar": "^2.0.3",
     "connect-history-api-fallback": "^1.5.0",
     "firebase-tools": "^3.17.7",
-    "rollup": "^0.57.1",
+    "rollup": "^0.60.2",
     "rollup-plugin-browsersync": "^0.2.6",
     "rollup-plugin-commonjs": "^9.1.0",
     "rollup-plugin-copy": "^0.2.3",