Add note about argparse
Add note about argparse

argparse is a Python module to help writing command-line argument.

In #247 we agree that SWC should not teach argparse but can
mention it.

selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest,selimnairb/2014-02-25-swctest