google: Fix removal of custom vCard attributes in Google address books
google: Fix removal of custom vCard attributes in Google address books

If a client had previously added a custom vCard attribute to a vCard in a
Google address book, subsequent removal of that attribute wouldn’t work,
since the backend wasn’t removing extended properties from the GData entries
when updating them.

Distrotech/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,matzipan/evolution-data-server,tintou/evolution-data-server,Distrotech/evolution-data-server,matzipan/evolution-data-server,Distrotech/evolution-data-server,tintou/evolution-data-server,matzipan/evolution-data-server