Added MetaType "GAPP" and made member_of of each APP

Added a variable called META_TYPE in settings.py as factory variable holding the value "GAPP"
changes done in filldb.py
  Now each APP(GSystemType)  contain member_of as  META_TYPE's id 
Changes done in ndf_tags.py in get_gapp_menu function
   Now menu created as follows:
1. Get all GSystemTypes with member_of GAPP's id(GAPP is a metatype)
2.Supply these GSystemTypes to build menu