[#618] Change "id" input name on plugin listing table to "plugin_sig"…

… which I believe is the key that should be transmitted to uniquely identify each plugin

tmpl/cms/list_plugin.tmpl

@@ -146,7 +146,7 @@
     </mt:if>
         <tr class="<mt:if name="__odd__">odd<mt:else>even</mt:if>">
             <td class="cb">
-              <input type="checkbox" name="id" value="<$mt:var name="id"$>" class="select" />
+              <input type="checkbox" name="id" value="<$mt:var name="plugin_sig"$>" class="select" />
             </td>
             <td class="name"><mt:if name="plugin_folder"><mt:var name="plugin_folder"><mt:else><$mt:var name="plugin_name" escape="html"$></mt:if></td>
             <td class="version"><$mt:var name="plugin_version" escape="html"$></td>