Adds report of test code with maven plugin by default.

JaCoCo maven plugin outputs coverage report with 'report' goal.
Now its report DOES NOT report coverage for test code.
Otherwise EclEMMA reports them.

I think test code coverage is needed to know if test code run enough.
So by default, as same as EclEMMA, I think they should include test code coverage.
If someone don't need them, they can use configuration of 'excludes' in 'report' goal.