Personnumers should not be mandatory

[Evgeny Kotelnikov]

Some of the exchange students, who stay in Sweden for only one semester, don't get a personnummer. We should add an option to the registration page that would allow them to only set a birthday instead (as it is usually asked in this situation). Furthermore, something should be done with the UNIQUE constraint on this field in the database then.

[Evgeny Kotelnikov]

We actually don't validate it very strictly, so currently the workaround is to put the birthday, followed by XXXX or something. Probably need a better solution still.