chore(package): update rollup-plugin-buble to version 0.15.0 (#285)

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -42,7 +42,7 @@
     "require-all": "^2.0.0",
     "rimraf": "^2.3.4",
     "rollup": "^0.36.0",
-    "rollup-plugin-buble": "^0.14.0",
+    "rollup-plugin-buble": "^0.15.0",
     "rollup-plugin-filesize": "^1.0.0",
     "rollup-plugin-uglify": "^1.0.0",
     "tape": "^4.2.2",