PropertiesChanged signal, take 2

[Luiz Augusto von Dentz]

Hi David,

Have you considerer PropertyChanged (only one property)? Afaik match
rules only support string matching so we will probably be unable to
register signal handlers in a per property basis, which IMO is a much
better design than PropertiesChanged which sends many, also at least
in BlueZ/ofono/connman Ive hardly see us updating a bunch of
properties at once and if that is required it is probably because they
should all be grouped together in a single property.

-- 
Luiz Augusto von Dentz
Computer Engineer