file chooser: Make sure places view type is known
file chooser: Make sure places view type is known

Similar to how we handle GtkPathBar, make sure that the
type for GtkPlacesView is registered before we load the
template.

https://bugzilla.gnome.org//show_bug.cgi?id=754133

jadahl/gtk,jadahl/gtk,chergert/gtk,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,jadahl/gtk,alexlarsson/gtk,jigpu/gtk,jadahl/gtk,chergert/gtk,grubersjoe/adwaita,jadahl/gtk,davidgumberg/gtk,jadahl/gtk,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,jadahl/gtk,alexlarsson/gtk,jigpu/gtk,alexlarsson/gtk,jigpu/gtk,chergert/gtk,grubersjoe/adwaita,davidgumberg/gtk,davidgumberg/gtk,alexlarsson/gtk,jigpu/gtk,alexlarsson/gtk,jigpu/gtk,jigpu/gtk,chergert/gtk,davidgumberg/gtk,grubersjoe/adwaita,davidgumberg/gtk,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,jadahl/gtk,grubersjoe/adwaita,alexlarsson/gtk,jigpu/gtk,jigpu/gtk,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,chergert/gtk