Fix Message attributes setters (fluent)

Author: gregoriohc

src/TwilioMmsMessage.php

@@ -15,9 +15,12 @@ class TwilioMmsMessage extends TwilioSmsMessage
      * Set the alphanumeric sender.
      *
      * @param $url
+     * @return $this
      */
     public function mediaUrl($url)
     {
         $this->mediaUrl = $url;
+
+        return $this;
     }
 }

src/TwilioSmsMessage.php

@@ -29,9 +29,12 @@ public function getFrom()
      * Set the alphanumeric sender.
      *
      * @param $sender
+     * @return $this
      */
     public function sender($sender)
     {
         $this->alphaNumSender = $sender;
+
+        return $this;
     }
 }