removed check against web service for install state of panel (when config file is there, installer installed it which assures that webserver is installed and configured - or someone messed around)

Implementation of detection override to configure webserver wheenver the panel is installed on the host regardless of user's preference

updater: db-query working, requests working. This will be my MR and hopefully fixes ispconfig/ispconfig3#4163 and hopefully also fixes ispconfig/ispconfig3#4050

Removed ubuntu1604.lib.php which is not required anymore.

- Introduced confid in $distver array to separate the config and class for a distribution in the installer.
- Cleaned up the dist detection.

Changed behaviour of UFW installation. Do not enable it by deafult as the firewall will get enabled autmatically when a firewall record gets added in ispconfig. Enabling it without that record, the Firewall would lock out the user on next reboot.