chore(package): update rollup to version 0.56.0

Author: greenkeeper[bot]

package.json

@@ -63,7 +63,7 @@
     "coveralls": "^3.0.0",
     "domdiff": "^0.3.6",
     "istanbul": "^0.4.5",
-    "rollup": "^0.55.0",
+    "rollup": "^0.56.0",
     "rollup-plugin-babel": "^3.0.2",
     "tressa": "^0.3.1",
     "uglify-js": "^2.8.29"