Changes to @hydra.main() and hydra.initialize()

Prior to Hydra 1.2, @hydra.main() and hydra.initialize() default config path was the directory containing the Python app (calling @hydra.main() or hydra.initialize()). Starting with Hydra 1.1 we give control over the default config path, and starting with Hydra 1.2 the default is config_path=None, indicating that no directory should be added to the config search path.