Visual Editor: Show loading animation while waiting for dom to load

[HeyJoel]

The visual editor boxes for modules can only display once the dom has fully loaded so it can work out where the editor boxed need to be. This can cause an issue if there are assets that take a long time to load. Perhaps we can show a discreet loader while the VE is waiting for the dom to load - maybe just an indicator in the toolbar.

Also the publish buttons did not load until the VE had rendered - shirly this does not need to wait until the dom is fully loaded.

This was a problem on a site that was timing out waiting for a font file to load and took 20s before the VE was available.