Bug fixing

There are no breaking changes or new features.

Bugfixes

• expose the rest of the logging functions associated with a level (debug, warning, etc..).
• add stdout/stderr filter so that logs lower than WARNING go to stdout instead of stderr.
• fix PickleHandler trying to write in files it finds in log_dir by adding a timestamp.
• fix MaxMetric constructor args.
• fix import exception handling for TensorBoard.

Other

• change the stream output formatter.