Fix some minor lint issues

This was shown by the testing that was added in merge request !34

manifests/preseeded_package.pp

@@ -1,3 +1,4 @@
+# Install a package with a preseed file to automatically answer some questions.
 define apt::preseeded_package (
   $ensure = 'installed',
   $content = ''
@@ -10,7 +11,9 @@ define apt::preseeded_package (
 
   file { $seedfile:
     content => $real_content,
-    mode    => '0600', owner => root, group => root,
+    mode    => '0600',
+    owner   => 'root',
+    group   => 0,
   }
 
   package { $name:

manifests/sources_list.pp

@@ -1,3 +1,4 @@
+# Configure an apt source
 define apt::sources_list (
   $ensure = 'present',
   $source = '',
@@ -22,7 +23,9 @@ define apt::sources_list (
   # apparently doesn't.
   file { "/etc/apt/sources.list.d/${realname}.list":
     ensure => $ensure,
-    owner  => root, group => 0, mode => '0644',
+    mode   => '0644',
+    owner  => 'root',
+    group  => 0,
     notify => Exec['apt_updated'],
   }
 

manifests/upgrade_package.pp

@@ -1,3 +1,5 @@
+# Install a package either to a certain version, or while making sure that it's
+# always the latest version that's installed.
 define apt::upgrade_package (
   $version = ''
 ) {
@@ -23,7 +25,7 @@ define apt::upgrade_package (
   }
 
   exec { "apt-get -q -y -o 'DPkg::Options::=--force-confold' install ${name}${version_suffix}":
-    onlyif  => [ "grep-status -F Status installed -a -P $name -q", "apt-show-versions -u $name | grep -q upgradeable" ],
+    onlyif  => [ "grep-status -F Status installed -a -P ${name} -q", "apt-show-versions -u ${name} | grep -q upgradeable" ],
     require => Package['apt-show-versions', 'dctrl-tools'],
     before  => Exec['apt_updated']
   }