User defined logger for activity and campaign is redundant

[wigging]

To create a script for a zambeze activity and campaign, the user must create a logger such as:

# Setup and configure logger
logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)

ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)

fmt = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
ch.setFormatter(fmt)

logger.addHandler(ch)

This logger is then passed to the ShellActivity and Campaign objects. The logger should be created within the campaign class or elsewhere in zambeze. Instead of passing a logger object to the campaign class, an argument can be used to enable/disable logging for the campaign such as Campaign(enable_logging=True). Regarding the activity class, there is no reason to pass a logger to the activity so just remove the Activity(logger) argument.