Fix the inheritance structure of base::dns

These classes all need to inherit from each other or the include
methods we use don't work properly.  Recreate the inheritance
structure and use overrides to change the resolv.conf parameters.

Also fix a few coding style issues.

manifests/dns.pp

 # Defines the DNS configuration of a system.
 
 class base::dns {
-  base::dns::resolv_conf { "$fqdn": ensure => present }
+  base::dns::resolv_conf { $::fqdn: ensure => present }
 }
 
 # This class adds a reference to a local DNS caching server.
-class base::dns::cache {
+class base::dns::cache inherits base::dns {
   include base::dns::cache_packages
   
-  base::dns::resolv_conf { "$fqdn":
-    ensure    => present,
-    dns_cache => true,
-  }
+  Base::Dns::Resolv_conf[$::fqdn] { dns_cache => true }
 }
 
 class base::dns::cache_packages {
@@ -31,59 +28,47 @@ class base::dns::cache_packages {
 
 # This class is for servers at Livermore.  The resolv.conf puts the
 # Livermore dns server first in the search list.
-class base::dns::dr {
-  base::dns::resolv_conf { $fqdn :
-    ensure           => present,
-    first_dns_server => '204.63.227.68',
-  }
+class base::dns::dr inherits base::dns {
+  Base::Dns::Resolv_conf[$::fqdn] { first_dns_server => '204.63.227.68' }
 }
 
 # This class is for servers at Livermore.  The resolv.conf puts the
 # local caching server first and includes Livermore dns server.
-class base::dns::dr-cache {
-  include base::dns::cache_packages
-
-  base::dns::resolv_conf { $fqdn :
-    ensure           => present,
-    dns_cache        => true,
-    first_dns_server => '204.63.227.68',
-  }
+class base::dns::dr-cache inherits base::dns::cache {
+  Base::Dns::Resolv_conf[$::fqdn] { first_dns_server => '204.63.227.68' }
 }
 
+# RHEL6 requires a custom resolv.conf to deal with a single-threaded lookup
+# bug which reduces performance to a crawl for services like sshd.
+#
+# TODO: remove EL6 custom resolv.conf when this bug is fixed.
 define base::dns::resolv_conf (
   $ensure           = present,
   $dns_cache        = 'NONE',
   $first_dns_server = 'NONE'
 ) {
-  case $ensure {
-    'absent': {
-      file { '/etc/resolv.conf': ensure => absent }
-    }
-    'present': {
-      # RHEL6 requires a custom resolv.conf to deal with a
-      # single-threaded lookup bug which reduces performance to a
-      # crawl for services like sshd.  TODO: remove EL6 custom
-      # resolv.conf when this bug is fixed.
-      if $::lsbdistcodename == 'santiago' {
-        $set_dns_options = true
-        $dns_options     = 'single-request-reopen'
-      } else {
-        $set_dns_options = false
-      }
-      if $dns_cache != 'NONE' {
-        $set_dns_cache = true
-      } else {
-        $set_dns_cache = false
-      }
-      if $first_dns_server != 'NONE' {
-        $set_first_dns_server = true
-      } else {
-        $set_first_dns_server = false
-      }
-      # resolv.conf is constructed from a template
-      file { '/etc/resolv.conf':
-        content => template('base/dns/etc/resolv.conf.erb')
-      }
-    }
+  if $::lsbdistcodename == 'santiago' {
+    $set_dns_options = true
+    $dns_options     = 'single-request-reopen'
+  } else {
+    $set_dns_options = false
+  }
+
+  if $dns_cache != 'NONE' {
+    $set_dns_cache = true
+  } else {
+    $set_dns_cache = false
+  }
+
+  if $first_dns_server != 'NONE' {
+    $set_first_dns_server = true
+  } else {
+    $set_first_dns_server = false
+  }
+
+  # resolv.conf is constructed from a template
+  file { '/etc/resolv.conf':
+    ensure  => $ensure,
+    content => template('base/dns/etc/resolv.conf.erb'),
   }
 }