remove requirement on lsb package for sources.list file

Managing requirements for installing the lsb package has proven over
time to make no sense. The best approach to this is to require
lsb-release to be installed alongside puppet, since otherwise there are
so much facts that get no value during the run and you end up needing to
run puppet twice to get the real end result.

Also, since we're not including a class that is actually installing the
'lsb' package, that require line makes it so that including the apt
module doesn't work, and there's no documentation in the README about
needing to provide a package{'lsb':} resource with the apt class.

Because of all that, it makes more sense to just get rid of that require
line and mark lsb as a pre-requirement in the README file.

README

@@ -99,9 +99,9 @@ Requirements
 
 This module needs:
 
+- the lsb-release package should be installed on the server prior to running
+  puppet. otherwise, all of the $::lsb* facts will be empty during runs.
 - the common module: https://gitlab.com/shared-puppet-modules-group/common
-- the lsb module: https://gitlab.com/shared-puppet-modules-group/lsb
-  (optional but recommended, required on Ubuntu)
 
 By default, on normal hosts, this module sets the configuration option
 DSelect::Clean to 'auto'. On virtual servers, the value is set by default to

manifests/init.pp

@@ -50,7 +50,6 @@ class apt(
     # additional sources should be included via the apt::sources_list define
     '/etc/apt/sources.list':
       content => $sources_content,
-      require => Package['lsb'],
       notify  => Exec['refresh_apt'],
       owner   => root,
       group   => 0,