Simplified the logic with color setting for user.

It is not helpfull to have such a confusing logic for coloring the user
part of the prompt and it doesn't behave as expected. Now if I set
LP_USER_ALWAYS to 0 it will not show me the user part, no matter what
user I use. Also there really isn't any point in always evaluating if
the user is not the login one.
Removed the setting for disabling VCS feaures only for root

There really isn't any point to disable VCS for root if you're really
using it. This setting adds logic wich complicates the script and
consumes clocks unnecessary. If you don't use VCS just disable it.
Removed the chroot detection as it was specific to Debian

Not only this was specific to Debian but also it's has to be setup in a
certain way which very few people use. I think we should try to have
features that are not distro dependent and that would be used on a
larger scale than just a few isolated cases. Removing it shoul save some
CPU cycles for the vast majority of users.