Support auto-timezone, delete cryptlib.key and ssl.cert when changing syspass

If the timezone is set to automatic and it's not a new install, don't display
"UTC0:01" as the time zone (that's weird), display "Automatic (UTC[+/-]HH:MM)"
instead.

When changing the system password via this config wizard, the cryptlib.key
and ssl.cert files, if they exist, will be invalid, so delete them.