obexd: Fix handling empty fields in vCards
obexd: Fix handling empty fields in vCards

Previously even mandatory TEL field was not printed in vCard if it was
empty. This patch fix this. Now tag TEL will be printed if phone number
is not set in phonebook. This patch also fix handling category string
for vCards in version 2.1 for url field.

mapfau/bluez,silent-snowman/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,pkarasev3/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,mapfau/bluez,mapfau/bluez,ComputeCycles/bluez,mapfau/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,silent-snowman/bluez,pkarasev3/bluez,ComputeCycles/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez