Switch support of Import Images as Planes add-on to OFFICIAL.

As discussed during bconf, have been maintaing that one for years now,
and it's quiet widely used...

io_import_images_as_planes.py

@@ -29,6 +29,7 @@ bl_info = {
     "warning": "",
     "wiki_url": "http://wiki.blender.org/index.php/Extensions:2.6/Py/"
                 "Scripts/Add_Mesh/Planes_from_Images",
+    "support": 'OFFICIAL',
     "category": "Import-Export",
 }