Merge pull request #795 from kaysoky/BetterAuthTestCase

Better auth test
Merge pull request #782 from kaysoky/DiffErrorCodeOnExpiredToken

Resend registration email
Add parameter (default false) for creating a user if it doesn't exist already
NotFoundException should be easier to parse :)
+ Comment
Add welcome message email
Have to intercept emails in the SendMail class, not in EmailUtils
POST /user with an existing user should throw a 409, not a 401
Change the location where the NameConflict is thrown to the manager layer