Added a new interface with a method that is called when the value is to
be saved into a resource configuration.
If the function returns false, then the default implementation of
handling property changes will kick in. If the function returns true,
then it's assumed that the value has been handled.
Change-Id: I0523d15ba0a3ec9dbc24c3e4afc070b071d8fb7e
Signed-off-by: Torbjörn Svensson <azoff@svenskalinuxforeningen.se>
