Dynamic property assignment deprecated (Log.php)

It looks like the pre-defining of the property $sensitiveStringRegexes was omitted at the top of the class net\authorize\util\Log

```
class Log
{
    private $sensitiveXmlTags = NULL;
    private $sensitiveStringRegexes = NULL; // line added
    private $logFile = '';
/*....*/

```
In newer versions of PHP it throws a deprecated warning
