Fixed startDate - only date, no time

Fixed startDate to only take the date portion from API response, and ignore the time.

Author: khaaldrogo

lib/net/authorize/api/contract/v1/PaymentScheduleType.php

@@ -73,7 +73,8 @@ public function getStartDate()
      */
     public function setStartDate(\DateTime $startDate)
     {
-        $this->startDate = $startDate;
+        $strDateOnly = $startDate->format('Y-m-d');
+        $this->startDate = \DateTime::createFromFormat('!Y-m-d', $strDateOnly); 
         return $this;
     }