reTurn: add support for comments in users.txt, more logging

git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@10773 ddefafc4-47db-0310-ae44-fa13212b10f2
reTurn: add comments about generating DH parameter file

git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@10774 ddefafc4-47db-0310-ae44-fa13212b10f2
reTurn: periodically check for updates to the user database file

git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@10775 ddefafc4-47db-0310-ae44-fa13212b10f2