chore(package): update rollup to version 0.49.3 (#1415)

Author: greenkeeper[bot]

package.json

@@ -42,7 +42,7 @@
     "local-web-server": "2.2.4",
     "markdown": "^0.5.0",
     "pdfjs-dist": "1.9.523",
-    "rollup": "0.46.0",
+    "rollup": "0.49.3",
     "rollup-plugin-babel": "3.0.0",
     "uglify-js": "3.0.27"
   },