Error not specified at patron creation

[pronguen]

When I create a patron, I cannot save it because of an unknown error (see screenshot).

[iGormilhit]

@pronguen I think it's related to the date. This field has a "format": "date" which, apparently, doesn't accept 9999-99-99.

Edit: Year 9999 is possible, of course, but Month > 12 and Day > 31 aren't.

At least, a better validation message should be provided.

[pronguen]

Could you please:

• change the regex (for ex. ^\d{4}(-(0[1-9]|1[0-2]))(-(0[1-9]|[1-2][0-9]|3[0-1]))$)
• add an error message, just in the case a wrong date is not checked by the regex (like 2018-02-30)?

[iGormilhit]

How to test:

1. Checkout into the branch
2. Review the commit
3. Create a user (user, patron, staff) and see how the birth date is validating