Add files generated by xpi task to clean task.
Add files generated by xpi task to clean task.

itplanes/uproxy,MinFu/uproxy,chinarustin/uproxy,uProxy/uproxy,IveWong/uproxy,itplanes/uproxy,jpevarnek/uproxy,qida/uproxy,itplanes/uproxy,jpevarnek/uproxy,IveWong/uproxy,uProxy/uproxy,IveWong/uproxy,dhkong88/uproxy,chinarustin/uproxy,dhkong88/uproxy,chinarustin/uproxy,qida/uproxy,dhkong88/uproxy,jpevarnek/uproxy,uProxy/uproxy,roceys/uproxy,itplanes/uproxy,MinFu/uproxy,roceys/uproxy,chinarustin/uproxy,jpevarnek/uproxy,MinFu/uproxy,uProxy/uproxy,itplanes/uproxy,IveWong/uproxy,qida/uproxy,roceys/uproxy,dhkong88/uproxy,chinarustin/uproxy,roceys/uproxy,jpevarnek/uproxy,MinFu/uproxy,qida/uproxy,roceys/uproxy,dhkong88/uproxy,MinFu/uproxy,uProxy/uproxy,qida/uproxy