Update tasks configuration to run checks locally when requested

Currently CheckStyle and RAT are run with almost every single Ant target, which is annoying as when developing locally. The targets should be clear - "test" - runs the tests, "jar" - builds the project and creates jars, and then we should have a task "check" which runs all the static analysis, that is CheckStyle, RAT and Eclipse-Warnings (or whatever we decide to replace Eclipse-Warnings with).

Such goal should be include in "artifacts" and we should run it instead of "eclipse-warnings" on CircleCI. This way building, static analysis and testings are clearly separated.