Fix CPUShares configuration option

This fixes the error message "Unknown or unsupported cgroup attribute
CPUShares".
man: link to XKB conf. guide in localectl(1)
man: fix display of keys which appear in two sections in directive index

When an index key appeared in multiple sections (e.g.
CPUAffinity= was present in both "SYSTEM MANAGER DIRECTIVES"
and "UNIT DIRECTIVES"), when lxml was used, the key would
be not be displayed in all but one of those sections, and
only an empty <term/> element would be present. This
happens because lxml allows only one parent for each node,
and when the same formatted element was used in multiple places,
it was actually moved between them. Fix this by making a copy
of the element. The bug was present since lxml support was
introduced.

Also fix some indentation issues.
core: use the same test as upstart for apparmor

Lennart:
> Hmm, I just noticed this patch:
>
> https://code.launchpad.net/~mdeslaur/upstart/apparmor-support/+merge/164169
>
> It contains a different check for AppArmor. Basically something like this:
>
> /sys/module/apparmor/parameters/enabled == 'Y'
>
> I'd prefer if we could change our code to do the same, given that
> the Ubuntu guys are guys are upstream for apparmor.

https://bugs.freedesktop.org/show_bug.cgi?id=63312
build-sys: more pretty colors
journald: DO recalculate the ACL mask, but only if it doesn't exist

Since 11ec7ce, journald isn't setting the ACLs properly anymore if
the files had no ACLs to begin with: acl_set_fd fails with EINVAL.

An ACL with ACL_USER or ACL_GROUP entries but no ACL_MASK entry is
invalid, so make sure a mask exists before trying to set the ACL.