Split JmxUtils class into smaller classes with similar responsibilities. Each extracted class has at least 80% ligne coverage.

This refactoring touches a lot of classes, but is very mechanical and introduces only very limited risk of regression.
Removed star imports as requested by @lookfirst

Checkstyle rule implemented to prevent star imports
Merge pull request #163 from gehel/improve-test-coverage

Split JmxUtils class into smaller classes with similar responsibilities....