Propagate Guzzle exception when rethrowing and remove redundant constructor

src/Gbif.php

@@ -52,7 +52,7 @@ abstract class Gbif {
       $response = $this->gbifClient->get($uri, ['query' => $query_string]);
     }
     catch (ClientException $e) {
-      throw new GbifException($e->getResponse()->getBody()->getContents());
+      throw new GbifException($e->getResponse()->getBody()->getContents(), $e->getCode(), $e);
     }
 
     $data = (string) $response->getBody();

src/GbifException.php

@@ -6,12 +6,4 @@ namespace ResTelae\Gbif;
  * GBIF: exception handler.
  */
 class GbifException extends \Exception {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function __construct($message = '', $code = 0, \Throwable $previous = NULL) {
-    parent::__construct($message, $code, $previous);
-  }
-
 }