Delete LTAM code

[rhansen]

LTAM has been superseded by SLURM so all of the LTAM code is now obsolete. It was never documented to users as being available, so quietly delete all of it.

This makes it easier to clean up the certificate verification code to fix issue #29.

[rhansen]

@dseomn: I'd love to get a quick thumbs-up or -down from you if you're available. There's no need to review the changes unless you want to.

A possibly controversial change: I silently deleted the LTAM database flags without providing a check in bin/rpki/upgrade.in to see if the database contains any paracertificates. I may add a check before merging this in, but I don't know if it's worth spending the time.

[dseomn]

@rhansen: Thumbs-up to removing LTAM code. I haven't reviewed this diff itself though. Adding a check to bin/rpki/upgrade.in and bailing if LTAM is in use should be relatively easy, if you get around to it. You could use a query something like select 1 from rpki_cert where ... limit 1 (replace ... with a flags test). If that query returns nothing, then LTAM is not in use, so proceed; otherwise it is, so bail.