Moved all classes to separate files (1 class per file policy).
Renamed the classnames: Prefixed with module name, "Create" instead of "Migrate".
Grouped all content creation classes in the "c4m_demo_content" group.
Update scripts so they support loading the dummy data during site install/upgrade & reset.
Updated the README about the -d option when installing/upgrading the platform.
Merge branch 'feature/CFD-37-create_dummy_content' into feature/CFD-38-dummy_article_content