testIsValid depends on the speed of Runtime's exec: sometimes it's quick
and passes (because it changes the date correctly) and sometimes is
not. A waitFor doesn't fix the issue, it waits forever.

This makes sure that if a a certificate is not valid, a new one is
downloaded. Unit tests don't apply to this, I've already added one to
the certificate validator, whose result will determine if a new
certificate will be downloaded.

Before we add a new profile, we check if there are any duplicated ones
with the same server IPs and ports. If they've the same credentials of
the new one, we don't add anything; if not, we remove the old ones and
add the new.