fix(package): update promise to version 8.1.0

Closes #83

Author: greenkeeper[bot]

package.json

@@ -56,7 +56,7 @@
     "osenv": "^0.1.3",
     "postcss-loader": "1.1.1",
     "progress": "^1.1.8",
-    "promise": "^7.1.1",
+    "promise": "^8.1.0",
     "react-hot-loader": "^3.0.0-beta.6",
     "read-metadata": "^1.0.0",
     "recursive-readdir": "^2.1.0",