2.0.0

BC break:

• remove ability to call execute statically

  Before:

  $response = SafeCurl::execute($url, $curlHandle);

  After:

  $safeCurl = new SafeCurl($curlHandle);
  $response = $safeCurl->execute($url);

Other ones:

• use PSR-4
• add travis & scrutinizer
• fix README
• add full coverage tests