[youtube] Remove X-GData-Client header
[youtube] Remove X-GData-Client header

It was deprecated on 2010-03-22, so we might as well save the bandwidth and
not send it with every request.

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