Replaces OptionParser with ArgumentParser

The optparse module is deprecated
(http://docs.python.org/2/library/optparse.html) and should be replaced
by argparse

I also took the liberty to add an example on where to get the argument
in the Project class
Updated the tests
PEP8 fixes
Merge pull request #6 from lra/argparse

The optparse module is deprecated and has been replaced by argparse. Code reformatted to comply with PEP8.