[introspection] Add missing annotations to GDataService
[introspection] Add missing annotations to GDataService

Pecisk/libgdata-gtasks,Pecisk/libgdata-gtasks,Distrotech/libgdata,Pecisk/libgdata-gtasks,pwithnall/libgdata,Pecisk/libgdata,pwithnall/libgdata,GNOME/libgdata,Pecisk/libgdata,Distrotech/libgdata,Pecisk/libgdata,Distrotech/libgdata