WL-3134 Make sure we don't leave templates around.

If the user cancels the creation of a site based on a template before it's created the process can crash out with a NPE (never seen by the user), but this results in the final part of the creation process never happening.

Crucially the final part removes the template property from the new site and if this isn't done the new site remains listed as a template.
Merge pull request #12 from ox-it/WL-3134

WL-3134 Make sure we don't leave templates around.