Bump up GnuPG's warning about the homedir

Previously, we would Enable GnuPG if you had gpg in your path and then
spit out a debug warning on startup because you don't have
/opt/rt4/var/data/gnupg.

We now only Enable => 1 GnuPG if you --enable-gpg or if you do it
manually.  As such, you're expecting GnuPG to stay enabled and any
warnings about why RT is disabling it should come at a higher log level.

S/MIME uses info for this message, so I went for parity.