backported Ubuntu changes into res files

changes originally done by DrDinosaur
[ubuntu] adds system settings
[ubuntu] improve apt-get instructions

setting up proper sources and other setting choices
[dev] users should have passwords

manually setting passwords that meet password policy should fix users with empty or weak passwords
[dev] improve user group instructions
[dev] improve user management instructions
[dev] rearrange items in ubuntu guide

- default groups and users to reference section
- users config before groups config
Merge branch 'ubuntu' into dev