Add java compatibility configuration

[metint]

Partially fixes jenkinsci/peass-ci-plugin#210

[metint]

@DaGeRe I checked the code and I realized that the compatibility related modification is already executed only if isUseAnbox() returns true. So it shouldn't effect the other users.

[DaGeRe]

You're right, than this is fine, I'll merge it.

In general, it would be nice to have more fine-grained methods (currently, methods tend to be a big lengthy). I'll have a quick look at it and refactor it where possible.

[DaGeRe]

To improve the readability, I extracted the GradleBuildfileEditorAnbox: https://github.com/DaGeRe/peass/blob/develop/dependency/src/main/java/de/dagere/peass/execution/gradle/GradleBuildfileEditorAnbox.java Feel free to further improve the structure.

[metint]

Thank you. I will also have a detailed look paying attention to method lengths later.