Fix Buzz Integration Failing Tests

* `$url` in `Client::doRequest(...)` uses https protocol
* `Client::doRequest(...)` has default parameter values for `$params` and `$data`. Both default to an empty array as they were previously (see https://github.com/algolia/algoliasearch-client-php/blob/master/algoliasearch.php#L806)
* Set `CURLOPT_FAILONERROR` to `false` as it was previously.
* Fixed calls to `AlgoliaTestCase::safe_name(...)` and `AlgoliaTestCase::containsValue(...)`
* `Client` methods call `Client::request(...)` not `Client::doRequest(...)`
* Fixed certificate path `CURLOPT_CAINFO` to `__DIR__ . '/../../resources/ca-bundle.crt'`
* Marked `FunctionTest::testKeepAlive()` as skipped

Using the http protocol results in an AlgoliaException:
```php
1) AlgoliaSearch\Tests\BasicTest::testAddObject
AlgoliaSearch\AlgoliaException: This method is only available in HTTPS
```