Refactoring: Databases, DBExecutor, MessageHandler, DataSources

beat/backend/python/data.py

beat/backend/python/database.py

beat/backend/python/dbexecution.py

beat/backend/python/hash.py

beat/backend/python/helpers.py

beat/backend/python/inputs.py

beat/backend/python/message_handler.py

beat/backend/python/test/mocks.py

beat/backend/python/test/prefix/databases/crash/1.json

beat/backend/python/test/prefix/databases/crash/1.py

beat/backend/python/test/prefix/databases/integers_db/1.py

beat/backend/python/test/prefix/databases/syntax_error/1.py

beat/backend/python/test/prefix/databases/valid/1.json

beat/backend/python/test/prefix/databases/valid/1.py

beat/backend/python/test/test_algorithm.py

beat/backend/python/test/test_data.py

beat/backend/python/test/test_data_loaders.py

beat/backend/python/test/test_database_view.py

beat/backend/python/test/test_dbexecutor.py

beat/backend/python/test/test_executor.py