Topology submitters should be able to supply log4j2 configurations

As a topology submitter, I would like to submit a log4j2 configuration alongside my topology to easily control my application's logging parameters. 

For example, I might need to reduce the log level of a particularly noisy dependency. Or, I might want to add a filter to drop these messages.

Since log4j supports composite configurations, Storm could support the user passing in a log4j2.xml file to be combined with the 'default' log4j2.xml.