contrib/lisp/org-contacts.el: Add a feature, which can ignore emails or phones with property
* contrib/lisp/org-contacts.el (org-contacts-ignore-property): New variable.
(org-contacts-remove-ignored-property-values): New function, which
remove all ignore-list's elements from list.
(org-contacts-complete-name): When completing, ignore the
values which has been included into the ignore property.
(org-contacts-vcard-format): Don't export the values which has
been included into the ignore property.
If emails or phones is included into the ignore property, they will
not show in complete buffer. When the contact is exported to vcard,
they will be ignored too.