Merge pull request #2 from hans00/master

Use correct format to post data.

src/Adapter/Guzzle.php

@@ -50,7 +50,7 @@ class Guzzle implements Adapter
     {
         $response = $this->client->post($uri, [
                 'headers' => $headers,
-                'form_params' => $body
+                'json' => $body
             ]
         );
 
@@ -125,4 +125,4 @@ class Guzzle implements Adapter
             throw new ResponseException("Request was unsuccessful.");
         }
     }
-}
+}

tests/Adapter/GuzzleTest.php

@@ -47,7 +47,7 @@ class GuzzleTest extends PHPUnit_Framework_TestCase
         $this->assertEquals("application/json", $headers["Content-Type"][0]);
 
         $body = json_decode($response->getBody());
-        $this->assertEquals("Testing a POST request.", $body->form->{"X-Post-Test"});
+        $this->assertEquals("Testing a POST request.", $body->json->{"X-Post-Test"});
     }
 
     public function testPut()