CAPTCHA_LENGTH=0 disables captchas

Change-Id: I4c7ec6e2176019a86240bfda3cbabe3644a7afe6
diff --git a/templates/register.htm b/templates/register.htm
index dd3c255..60b7bd5 100644
--- a/templates/register.htm
+++ b/templates/register.htm
@@ -162,6 +162,8 @@
             </div>
         </div>
     </div>
+
+    <?php if($CAPTCHA_LENGTH > 0): ?>
     <!--captcha here-->
     <div class="form-outline mb-3">
         <label class="form-label font-weight-bold" for="form3Example4">Captcha</label>
@@ -179,6 +181,7 @@
                 Type what you see on the image above.
             </div>
     </div>
+    <?php endif; ?>
 
     <!-- Submit button -->
     <div class="container mt-2 text-right">