Set first edition org to current users org

If there are no lead orgs for an edition add the first lead org as the
current users org. The default case is that users will want to create
content for their own organistion.

https://www.pivotaltracker.com/story/show/48759205
Merge pull request #550 from alphagov/default-edition-orgs

Set first edition org to current users org

https://www.pivotaltracker.com/story/show/48759205