Refactoring of HarvestScheduler related code

The purpose of this issue is to act as log for the different refactorings done in in the course of implementing NARC-11.

• Introducing Component lifecycling replace cleanUpIF and singleton usage, see CleanupIF vs. Singleton an The weakness of the CleanupIF discussions.
• Splitting the current HarvestScheduler into the following class's:
  • A HarvestJobGenerator
  • A HarvestJobDispatcher (Actually the remains HarvestScheduler)
  • A HarvestDatabaseBackup class (Not extracted from the HarvestScheduler yet).
    All three components are running their tasks on a regular basis (scheduling). I have not reflected this in the class names, as components should preferable be named after their business domain responsibilities, rather than software design details (scheduler, client, etc). The creation and lifecycling of the components are handled by a HarvestJobManager, which I'm planning on should act as the standalone HarvesterSchedulerApplication mentioned in 'Feature request 1963 Make a HarvestSchedulerApplication that runs the HarvestScheduler'.

The refactoring done on the harvestscheduler-refac branch, where the concrete changes can be viewed.