Release 0.0.4

Added

• Adds _find_existing_package method to allow harvesters extending the HarvesterBase to implement their own logic to find an existing package
• Adds support for ITranslation interface
• Adds special CSS class to datetimes in frontend to enable localisation to the users timezone

Changed

• Make statistics keys consistent across all actions

Removed

• Remove harvest_source_for_a_dataset action