Certificates removed:
* 5.pem
* 6.pem
* 9.pem

In particulare the one in certs shows concrete examples on how to
generate VOMS proxies

The proxies had a wrong VO in the FQANs and couldn't be validated any
more by the VOMS lib. See commit
https://github.com/italiangrid/voms/commit/feeaed

encoding.t was also affected, but didn't require any change, just a
correctly generated proxy.

And related test.