Loosen up restrictions on dependency token names (rhbz#455119)

Loosen up restrictions on dependency token names (rhbz#455119)
- Package names aren't restricted to ascii, no point restricting
  dependency names either.
- This lets UTF-8 to go through but also all sorts of other junk but
  as we haven't got a clue about the specs encoding, no can do. So we
  only check for bad characters from plain ascii.