Return 403 Forbidden on duplicated username when registering

Closes #38 (closed)

assigned to @cthl58

assigned to @tksl38

assigned to @dgrh99

added 2 commits

• db357fd8 - 1 commit from branch master
• 1b27e93a - Return 403 Forbidden on duplicated username when registering

Compare with previous version

There are multiple reasons why UserServiceImpl#create could return null so I think the best thing to do here would be refactoring the method to throw Exceptions.

But that is something for another MR. See #5.

LGTM

mentioned in commit efb199bc

merged