Code style checks

Concerning the reformat tasks: In a CI environment, it is rarely desirable that source files are modified. However, it would still be helpful if there would be a task which only checks whether the source files comply to the coding styles (formatting, organize imports, etc.) specified in the IDEA project. Having a task which actually applies the coding style is still useful for the developers locally.

Consider using Gradle's incremental task inputs so that only files are checked which where actually changed.

Thanks! I'd love to have a well working and fast IDEA integration for Gradle so that our team could switch from a many inspection plugins solution to a single one and convincing them of the many benefits of IDEA.