Upgrade electron to v1.6.0 (beta)

Author: jhen0409

package.json

@@ -37,7 +37,7 @@
     "babel-preset-stage-0": "^6.5.0",
     "cross-env": "^3.1.3",
     "devtron": "^1.2.0",
-    "electron": "^1.4.15",
+    "electron": "^1.6.0",
     "electron-debug": "^1.0.0",
     "electron-devtools-installer": "^2.1.0",
     "electron-packager": "^8.2.0",