Initial push of a minimal nih-based dbus service

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Fix dbus path and add more examples

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Add exception example

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>