main: instantiate a afm_user_daemon proxy

* Create a single org::AGL::afm::user instance.
* Do not make use of static object construction/destruction.
* Use QScopedPointer in main() to manage the resource.
* Users of this instance use an extern declaration of the global
  variable.

Change-Id: Ia6db7aae8c8f6b135fe62bda495c68fdef004081
Signed-off-by: Marcus Fritzsch <marcus_fritzsch@mentor.com>