Lazily create a UserProfile after purchase (# 1027283)

- Query transaction in Solitude to look up buyer
- Query buyer to find user email
- Create a UserProfile for that email
- Add/Update tests
oh, heh, it was just a question. Actually we don't know if the user is verified or not! Verified means that the user clicked the confirmation link in their email reader. I think for now we can leave it as False but you should file a bug to change this to True once we migrate to Firefox Accounts.