fix VOMS-516
fix VOMS-516

The fix is mostly based on the patch provided by Matthias.
In addition the CN is now based on the SHA1 of the *request*
public key. The same string is also used for the serial number.

ellert/voms,italiangrid/voms,italiangrid/voms,giacomini/voms,ellert/voms,giacomini/voms,ellert/voms,italiangrid/voms,giacomini/voms