package.json: Upgrade electron one more time

package.json

@@ -56,6 +56,6 @@
     "rollup": "^0.43.0",
     "rollup-watch": "^4.0.0",
     "uglify-js": "^3.0.23",
-    "electron": "^1.6.14"
+    "electron": "1.7.8"
   }
 }