full support for all the multi-valued elements

Supports all the remaining multi-valued elements: URLs, Social Profiles, IM Profiles.

I converted the support for email addresses and phone numbers to use the same MultiValued class as these others.  This means that I had to remove the unitary "email" and "phone_number" methods, you much fetch a list of email_values or phone_values.

And I've broken the ability to assign values for individual email/phone entries like `@ab_person.mobile_phone = xxxx`.  You have to assign the entire list of values with `:label` parameters for each.

Search on email address does work - it will compare against all the email addresses on each Person record. But search on phone, URL etc. are not currently functional.

Not really satisfied with this, but I haven't come up with a better idea that can handle all the possible stuff that can accumulate in AB records.