Refactoring of unattended-upgrades

Refactory of the unattended-upgrade function for apt.
Added many options that can be useful when selection new repository from which do autoupdate, put packages in blacklist and do automatic reboot.

Changed also the creation of the file 50unattended-upgrades, it was previously created with the apt::conf define that generate files with .conf extension, so after the installation of the package the directory would end up with 2 configuration files

50unattended-upgrades
50unattended-upgrades.conf

This can cause some confusion and unwanted behaviours.