Add basic equality testing for FieldDetails.
Add basic equality testing for FieldDetails.

Helps: bgo#653679 - Change PostalAddressDetails.postal_addresses to
support vCard-like arbitrary parameters

GNOME/folks,renatofilho/folks,renatofilho/folks2,renatofilho/folks,pwithnall/folks,GNOME/folks,renatofilho/folks2,GNOME/folks,pwithnall/folks,renatofilho/folks2,pwithnall/folks,renatofilho/folks2,renatofilho/folks,renatofilho/folks