Failing tests due to missing id field

I followed your tutorials step by step, and the "id" field is required.
Thus the "add" route refused to "create" an album, because this "id" field was missing, resulting in a 200 response code.
In the mean time, PHPUnit complained because I was redirected to "/album/", and not "/album"
Merge branch 'hotfix/#1406-missing-slash-in-redirect-url'

Close #1406