Major cleanup for merge

CLI: added --format, supports 'prettytable' and 'raw'
CLI: Auto-detects isatty() and sets default for --format to 'raw'
CLI: CLIRunnable.execute() now expected to return CLI.Table
CLI: dns refactored to support all of the above, args unchanged
setup.py: Added argparse dependency for python<2.6
tox: removed jython
travis: removed jython