Aux modules no longer displayed in help by default

* clusterd.py
  -- Pass in the auxiliary option to check if we're printing
  a specific platform's modules
* src/core/auxengine.py
  -- Wrapped auxiliary runner in a try/except
  -- Moved execution of post-fingerprinting clusterd-specific modules
  into its own method; cleans up a bit
  -- Modified argument handler to always suppress
* src/core/auxiliary.py
  src/platform/*/auxiliary/
  -- Removed the show variable
* src/core/parse_cmd.py
  -- Updated the --aux-list flag to accept zero or one variable;
  if none is provided, all platform auxiliary modules will be listed.
  If a platform is provided, only that platforms modules will be
  printed.
* src/module/deploy_utils.py
  -- Check the aux-list flag