Client: allow usage of options

[glaubinix]

There is currently no way to change the timeout for the Curl client. Only way to do so is by setting a new client.

Current way:

$client = new \Gitlab\Client('https://gitlab.com/api/v3/');
$client->setOption('timeout', 1);
$client->setHttpClient(new HttpClient($client->getBaseUrl(), ['timeout' => 1], $curl));

Once this PR is merged you can simply do:

$client = new \Gitlab\Client('https://gitlab.com/api/v3/', null, ['timeout' => 1]);