Include more tests realeted to signature and upgrade.

 If still required, slapprepare is present on several tags.

Update Default Location, and minor style changes.

  Fix minor typo changes on distribution.py

  Run slapos node collect every minute to take servers
  snapshot.

  This script is risky, and the number of legacy servers with openvpn
  is small, so manual migration is more worth.

  SlapOS should not depends on re6st in any sense.

  Include API Support for download keys/gpg slapos.