core: PropertyChanged signal for Icon/Appearance
core: PropertyChanged signal for Icon/Appearance

This patch emits the PropertyChanged signal in the Device hierarchy when
the remote device Appearance characteristic is read. In general
Appearance is a static value, if the device doesn't expose the
Appearance value in the advertising data, the GAP plugin should read the
value using GATT read procedure.

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