This adds a new boolean field "public_details" to person model.
By default it is false and represents old behaviour. When it is
set to true, extended profile (bio,location,gender,birthday)
get available to people who didn't log into diaspora and to
people you don't share with (i.e. it is made public).

In UI, a bootstrap-switch added on the profile-edit page in order to
change the setting.

This also changes wording from public/private profile to basic/extended.
The latter could be public and limited.