[2.0] Refactored classloader architecture. Renamed ClassLoader => GlobalClassLoader. Introduced IsolatedClassLoader that is suitable for participating in autoload stacks. Added 2 example entity classes to the sandbox with 2 xml mappings and 2 yaml mappings. Simplified sandbox setup.

[2.0] Work on CLI: Added SchemaToolTask with preliminary support for dropping/creating the database schema. Prepared the sandbox. Adjusted build to include the sandbox.