Agreement Form Data Content Type

* A request for the agreement form data requires a content type to be
set even if it doesn't match our request. This matches the behavior of
the swagger api docs.

src/Abstracts/Resource.php

@@ -255,11 +255,14 @@ protected function simpleGetRequest( array $queryString = [ ], $userId = null, $
      * @param array $query
      * @return bool
      */
-    protected function saveFileRequest( $saveToPath, array $query = [ ] )
+    protected function saveFileRequest( $saveToPath, array $query = [ ], string $content_type = null )
     {
         $request = new GetRequest( $this->getOAuthToken(), $this->getRequestUrl( $query ) );
         $request->setFileSavePath( $saveToPath );
         $request->setJsonRequest( false );
+        if (!is_null($content_type)) {
+            $request->setHeader('Content-Type', $content_type);
+        }
 
         $this->setRequest( $request );
         $this->logDebug( "GET: " . $this->getRequestUrl( $query ) );

src/Agreements.php

@@ -156,7 +156,7 @@ public function formData( $agreementId, $saveToPath )
     {
         $this->setApiRequestUrl( $agreementId . '/formData' );
 
-        return $this->saveFileRequest( $saveToPath );
+        return $this->saveFileRequest( $saveToPath, array(), 'application/json' );
     }
 
     /**

src/Transports/GuzzleTransport.php

@@ -52,7 +52,6 @@ public function handleRequest( HttpRequest $httpRequest )
             $options['multipart'] = $options['body'];
             unset($options['body']);
         }
-
 
         $url = $httpRequest->getRequestUrl();