QTZ-314 : quartz integration tests may fail because of the derby db files not being deleted -- if using maven, the target directory will be used to store the db; if using something else, such as the IDE, java.io.tmpdir will be used
QTZ-225 : Make the Scheduler's ClassLoadHelper available to plugins when they are initialized The SchedulerFactory(ies) now have to initialize the plugins with their ClassLoadHelper instance, that way the plugins can see the same classes that the scheduler factories can.