[db-wg] Phone number requirement for person objects

Hi,

In the DB-WG interim session I mentioned that there's currently a
discrepancy between person objects and role objects with regards to
contact information.
More specifically, person objects currently require a phone number
while role objects require an email address.

I think we should try to bring person objects more in line with role
objects by removing the phone number requirement. Ideally I would want
it to be mandatory to have either a phone number or an email address
in order to not lose any flexibility but I'm not sure if that is
possible.

During the session I asked if anyone was opposed to the idea and no
one said they were so I would assume that this is relatively
uncontroversial but please let me know what you think.

-Cynthia