Make the (public) users api hyperlinked.
Merge remote-tracking branch 'origin/master' into hyperlink-users

Conflicts:
	user_management/api/serializers.py
	user_management/api/views.py
Add validate_email to UserSerializer.
Add date_joined to read_only_fields
Merge pull request #23 from incuna/hyperlink-users

Serializers should include a url (extend HyperlinkedModelSerializer)