OutputFormatter objects should have event for layer setUp/tearDown failure

Currently, OutputFormatter and friends has methods for start_set_up, stop_set_up, start_tear_down, stop_tear_down and tear_down_not_supported. However, it doesn't have methods to handle the cases when layer set up or tear down fails.

This is particularly bad for output formatters that produce output intended for automated reading. There's no natural way to hook into layer errors and report them gracefully.

To fix this, OutputFormatter, ColorfulOutputFormatter and SubunitOutputFormatter should grow methods set_up_failed and tear_down_failed. Meanwhile, tear_down_unneeded and setup_layer in runner.py should be changed to call these new methods in the case of layer setUp/tearDown failure.