Udisks2: and corresponding properties when an interface is added

Currently when receiving a new interface, the interface is added to the interfaces known list for the device but nothing else happens, users are not informed and new properties are not loaded.

With this patch, the device will emit changed() and propertyChanged() accordingly if properties have changed.

The current state is semantically incorrect as documentation clearly implies it should be necessary to change as needed the reflected state of the Solid::Device.

Note that interfaces may be added and removed at run-time. http://storaged.org/doc/udisks2-api/latest/ref-dbus-block-devices.html

A signal listener to Device::propertiesChanged and/or Device::changed must be added to KFilePlascesItem so that properties are reflected in use-places.xbel.