Update recaptcha.php

Pull request based on the issue tracked as zero-24 asked:

http://issues.joomla.org/tracker/joomla-cms/7921

plugins/captcha/recaptcha/recaptcha.php

@@ -118,13 +118,25 @@ public function onCheckAnswer($code = null)
 		{
 			case '1.0':
 				$challenge = $input->get('recaptcha_challenge_field', '', 'string');
-				$response  = $input->get('recaptcha_response_field', '', 'string');
+
+ 				//We check the override $code param
+                                if (!empty($code))
+                      		    $response = $code;
+                		else
+         			    $response  = $input->get('recaptcha_response_field', '', 'string');
+
 				$spam      = ($challenge == null || strlen($challenge) == 0 || $response == null || strlen($response) == 0);
 				break;
 			case '2.0':
 				// Challenge Not needed in 2.0 but needed for getResponse call
 				$challenge = null;
-				$response  = $input->get('g-recaptcha-response', '', 'string');
+
+ 				//We check the override $code param
+		                if (!empty($code))
+                		      $response = $code;
+                		else
+         			      $response  = $input->get('g-recaptcha-response', '', 'string');
+
 				$spam      = ($response == null || strlen($response) == 0);
 				break;
 		}