Check for safe_mode or open_basedir in the cURL adapter

Certain environments with PHP's `safe_mode` or `open_basedir` options set can cause errors with the cURL adapter.  Users will get a message similar to `Warning: curl_setopt_array(): CURLOPT_FOLLOWLOCATION cannot be activated when an open_basedir is set in /libraries/joomla/http/transport/curl.php on line 159`.