allow possibility of disabling backports

manifests/init.pp

@@ -7,6 +7,7 @@ class apt(
   $codename = $apt::params::codename,
   $use_lts = $apt::params::use_lts,
   $use_volatile = $apt::params::use_volatile,
+  $use_backports = $apt::params::use_backports,
   $include_src = $apt::params::include_src,
   $use_next_release = $apt::params::use_next_release,
   $debian_url = $apt::params::debian_url,

manifests/params.pp

@@ -2,6 +2,7 @@ class apt::params () {
   $codename = $::lsbdistcodename
   $use_lts = false
   $use_volatile = false
+  $use_backports = true
   $include_src = false
   $use_next_release = false
   $debian_url = 'http://httpredir.debian.org/debian/'

templates/Debian/sources.list.erb

@@ -19,14 +19,16 @@ deb-src <%= security_url %> <%= codename %>/updates <%= lrepos %>
 # There is no security support for <%= release %>
 <% end -%>
 
+<% if use_volatile=scope.lookupvar('apt::use_backports') -%>
 # backports
-<% if (release == "testing" || release == "unstable" || release == "experimental") -%>
+<%   if (release == "testing" || release == "unstable" || release == "experimental") -%>
 # There is no backports archive for <%= release %>
-<% else -%>
+<%   else -%>
 deb <%= backports_url=scope.lookupvar('apt::backports_url') %> <%= codename %>-backports <%= lrepos %>
-<%   if include_src -%>
+<%     if include_src -%>
 deb-src <%= backports_url %> <%= codename %>-backports <%= lrepos %>
-<%   end
+<%     end
+     end
    end -%>
 
 <% if use_volatile=scope.lookupvar('apt::use_volatile') -%>