Add 'samba::additional_config' option

This allows the user of the module to specify arbitrary server
configuration options. For example, in hiera:

    samba::additional_config:
      server_multi_channel_support: yes
      aio_read_size: 1
      aio_write_size: 1
      min_receivefile_size: 16384

README.md

@@ -53,6 +53,9 @@ This module is designed to be as clean and compliant with latest puppet code gui
       local_master         => 'yes',
       preferred_master     => 'yes',
       map_to_guest         => 'Bad User',
+      additional_config    => {
+        server_multi_channel_support => 'yes'
+      },
       shares => {
         'homes' => {
           comment    => 'Home Directories',
@@ -102,6 +105,8 @@ samba::local_master: 'yes'
 samba::preferred_master: 'yes'
 samba::map_to_guest: 'Bad User'
 samba::firewall_manage: true
+additional_config:
+  server_multi_channel_support: 'yes'
 samba::shares:
   'homes':
     comment: 'Home Directories'

manifests/config.pp

@@ -45,6 +45,13 @@
     'obey pam restrictions':    value => $samba::obey_pam_restrictions;
   }
 
+  $samba::additional_config.each | $option, $value | {
+    $option_with_spaces = regsubst($option, '_', ' ', 'G')
+    samba::option { $option_with_spaces:
+      value => $value,
+    }
+  }
+
   $samba::idmap_config.each | $idmap_domain, $idmap_options | {
     $idmap_options.each | $idmap_option, $idmap_value | {
       samba::option { "idmap config ${idmap_domain} : ${idmap_option}":