Declare dependencies of the scripts in examples/
Declare dependencies of the scripts in examples/

This allows e.g. `pip install python-u2flib-server[u2f_server]`.

The line containing `python_version=="2.6"` is an environment marker,
supported since setuptools 0.7 (released June 2013). `argparse` is in
the stdlib from Python 2.7.

Yubico/python-u2flib-server,moreati/python-u2flib-server