contacts: Add a code example for using batch operations
contacts: Add a code example for using batch operations

Helps: bgo#579885

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