configure.php: fix display of values

The construct <?= does not work in all PHP version, so replace this
by a more generic version <?php e

configure.php

@@ -151,17 +151,17 @@ foreach ($config_options as $key=>$value){
         <?php
     // the key starts with hr, then just display the value
       if(substr($key,0,7)=='heading'){ ?>
-          <th align="center" colspan="2"><?=$value?></th>
+          <th align="center" colspan="2"><?php echo $value?></th>
         <?php } else { ?>
-        <td align="right"><?=$value['description']?></td>
+        <td align="right"><?php echo $value['description']?></td>
         <td><?php
       switch($value['type']){
         case 'checkbox': ?>
-          <input type="checkbox" name="<?=$key?>" <?=$value['value']?"checked=\"checked\"":""?>>
+          <input type="checkbox" name="<?php echo $key?>" <?php echo $value['value']?"checked=\"checked\"":""?>>
           <?php
           break;
         case 'text': ?>
-          <input type="text" name="<?=$key?>" value="<?=$value['value']?>">
+          <input type="text" name="<?php echo $key?>" value="<?php echo $value['value']?>">
           <?php
           break;
         case 'select': 
@@ -185,8 +185,8 @@ foreach ($config_options as $key=>$value){
 ?>
     <tr>
         <td colspan="2" align="right">
-            <input type="Submit" name="Cancel" value="<?=$AppUI->_('cancel')?>">
-            <input type="Submit" name="Save" value="<?=$AppUI->_('save')?>">
+            <input type="Submit" name="Cancel" value="<?php echo $AppUI->_('cancel')?>">
+            <input type="Submit" name="Save" value="<?php echo $AppUI->_('save')?>">
         </td>
     </tr>
 </table>