Add HttpAccessLogFileScanner iterator

[codein-dev]

It's very common to analyze web access log files. So, if we support the HttpAccessLogFileScanner out of the box, it will be a very useful feature. Http access log file format is well standardized.

You can see the access log file format here: http://support.moonpoint.com/network/web/server/apache/log_format.php

https://en.wikipedia.org/wiki/Common_Log_Format