[FIX] Ignore master template on template editor

Don't use SQL templates for large amount of changes. Create your own
file based theme then!

This fixes #1375 once merged

public/templates/mpos/admin/templates/tree.tpl

@@ -1,5 +1,6 @@
 <ul>
   {foreach from=$files item="value" key="file"}
+  {if $file != 'master.tpl'}
   {if is_array($value)}
     <li class="folder">
       {$file}
@@ -21,5 +22,6 @@
       <a href="{$smarty.server.SCRIPT_NAME}?page={$smarty.request.page}&action={$smarty.request.action}&template={$prefix}{$file}">{$file}</a>
     </li>
   {/if}
+  {/if}
   {/foreach}
 </ul>