Created auth groups and roles

Signed-off-by: JWhy <jwhy@jwhy.de>
Added "Access denied" page

Signed-off-by: JWhy <jwhy@jwhy.de>
Remove array notice in HTML class when there's only one URI segment

Signed-off-by: JWhy <jwhy@jwhy.de>
Added admin entry to bootstrap navigation, improved navigation html output

Signed-off-by: JWhy <jwhy@jwhy.de>
Added menu to admin page (very basic) and created add user page

Signed-off-by: JWhy <jwhy@jwhy.de>