Test to specify licenseSet includes from CLI

[mathieu]

Added an IT test to reproduce the solution provided in #536. In the tri-license-set-with-includes integration test we have 3 licenseSets and would only need to format the Unformatted2.java file via the command line.

On needs to update the license-maven-plugin/src/it/tri-license-set-with-includes/invoker.properties files to test others ways of setting this.

It fails for me with the following variations:

invoker.goals=license:format -Dlicense.licenseSets.licenseSet.includes=src/main/java/com/mycila/it/Unformatted2.java
invoker.goals=license:format -Dlicense.licenseSet.includes=src/main/java/com/mycila/it/Unformatted2.java
invoker.goals=license:format -Dlicense.includes=src/main/java/com/mycila/it/Unformatted2.java