Facia tool: better concurrent editing

Alert when edits have been made by another user whilst an article on your own screen is in a open editable state (because the latter stops the collection from auto-refreshing)

![fronts-tool](https://f.cloud.github.com/assets/1147913/1912705/d4159b6c-7d3d-11e3-8c32-9d64e4881d6d.png)