Fixes for profiles and ISO-Date-Time

ISO Date Time is a bit too picky atm, but also isn't picky enough. I've
done a PR on https://github.com/sfx/schema-contrib and when that is
merged we can go back to using ISO-Date-Time.

The PR is here: https://github.com/sfx/schema-contrib/pull/4
Merge pull request #8 from MastodonC/feature/profile-fixes

Fixes for profiles and ISO-Date-Time