Make ArvCamera a proper GObject
Make ArvCamera a proper GObject

* Make device a construct only GObject property
* Do camera setup in arv_camera_constructor (move code that
  was in arv_camera_new here)

There is no change in behaviour nor API

https://bugzilla.gnome.org/show_bug.cgi?id=677710

Signed-off-by: Emmanuel Pacaud <bd234ba4276433f0e5fc7a8fa2d18274fa711567@gnome.org>

AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis