Added file iteration support

[fishermans]

Hello Karl-Heinz,

I spent some time improving your great iterated maven plugin to also support file iteration since it was already requested in #11 and need for some business cases I am working on. I am using it a lot in many builds.

I would really appreciate it if you could accept this pull request or even the approach of it. The changes are backward compatible except the minor JDK version 8. Thus, it won't break existing installations.

Maven wrapper has also been added.

Please see readme.md for details on how use file iteration and all the additional results it offers.

Thanks, Tiemo