Support shopware 6 plugins

Makes commands changelog and upload compatible with Shopware 6 plugins.
Makes the command compatibility fail when executed for a Shopware 6 plugin.
Fixes a bug that lead to a crash when trying to dump a plugin that does not exist.
Removes methods:
- ShopwareStoreCommander.getSalesForPlugin
- ShopwareStoreCommander.getCommissionsForPlugin

Closes #24

pickware / scs-commander