Adding more custom log readers

[Xuphey]

https://github.com/ua-parser/uap-php/blob/3004c494d204c3b6d5e1e80a4ff78e4025e24e2f/src/Util/Logfile/AbstractReader.php#L37

Could it be possible to let the factory read a directory of "LogReader" classes? I'd like to add few more reader classes without touching this code.