Adds delete credit card functionality

src/Transaction.php

@@ -253,6 +253,10 @@ public function valid()
                     $errors[] = Validator::set($params, 'pan') ? null : 'Credit card number not provided.';
                     $errors[] = Validator::set($params, 'expdate') ? null : 'Expiry date not provided.';
 
+                    break;
+                case 'res_delete':
+                    $errors[] = Validator::set($params, 'data_key') ? null : 'Data key not provided.';
+
                     break;
                 default:
                     $errors[] = $params['type'].' is not a supported transaction type.';

src/Vault.php

@@ -28,6 +28,8 @@ public function __construct(string $id, string $token, string $environment)
     }
 
     /**
+     * Add a credit card to the Vault.
+     *
      * @param \CraigPaul\Moneris\CreditCard $card
      *
      * @return \CraigPaul\Moneris\Response
@@ -46,6 +48,26 @@ public function add(CreditCard $card)
         return $this->process($transaction);
     }
 
+    /**
+     * Delete a credit card from the Vault.
+     *
+     * @param string $key
+     * @param \CraigPaul\Moneris\CreditCard $card
+     *
+     * @return \CraigPaul\Moneris\Response
+     */
+    public function delete(string $key)
+    {
+        $params = [
+            'type' => 'res_delete',
+            'data_key' => $key,
+        ];
+
+        $transaction = $this->transaction($params);
+
+        return $this->process($transaction);
+    }
+
     /**
      * Create a new Vault instance.
      *
@@ -61,6 +83,8 @@ public static function create(string $id, string $token, string $environment)
     }
 
     /**
+     * Update an existing credit card in the Vault.
+     *
      * @param string $key
      * @param \CraigPaul\Moneris\CreditCard $card
      *