Add PHP7 type annotations to Interfacing classes

src/main/edu/wisc/services/cbs/order/interfacing/MockOrderInterfacingService.php

@@ -30,7 +30,7 @@ class MockOrderInterfacingService implements OrderInterfacingService, MockServic
     /**
      * {@inheritdoc}
      */
-    public function interfaceOrder($orderNumber)
+    public function interfaceOrder($orderNumber): OrderServiceResponse
     {
         return $this->response;
     }

src/main/edu/wisc/services/cbs/order/interfacing/OrderInterfacingService.php

@@ -13,9 +13,9 @@ interface OrderInterfacingService extends Service
 
     /**
      * Commit and finalize ("interface") an order with CBS.
-     * @param string $orderNumber
+     * @param float $orderNumber
      * @return OrderServiceResponse
      */
-    public function interfaceOrder($orderNumber);
+    public function interfaceOrder($orderNumber): OrderServiceResponse;
 
 }
\ No newline at end of file

src/main/edu/wisc/services/cbs/order/interfacing/SoapOrderInterfacingService.php

@@ -45,7 +45,10 @@ class SoapOrderInterfacingService implements OrderInterfacingService, SoapServic
         }
     }
 
-    public function interfaceOrder($orderNumber)
+    /**
+     * {@inheritdoc}
+     */
+    public function interfaceOrder($orderNumber): OrderServiceResponse
     {
         $response = $this->soapClient->INTERFACE_ORDER(
             new InputParameters($orderNumber, "MAGE$orderNumber", 'TBD')