Update dependency reflux to v6

Author: renovate-bot

package.json

@@ -31,7 +31,7 @@
     "react-router": "^2.0.0",
     "react-tap-event-plugin": "^0.2.2",
     "react-tinymce": "^0.7.0",
-    "reflux": "^0.3.0",
+    "reflux": "^6.0.0",
     "reflux-state-mixin": "^0.6.3"
   },
   "devDependencies": {