WIP to be able to send HEAD and figure out when a key will expire

- Probably mad fucked up
- Frontend should work, backend requires a refactor because I was
  assigning stack-allocated times in ol_scoop which went out of scope
  and dissapeared.
Seems to be working the way I intended.
ol_content_type and ol_expiration now delete keys if they have expired
as well.
Various small bugfixes. GOOD ENOUGH!