tox.ini: Use {posargs} for commands
tox.ini: Use {posargs} for commands

Lets you pass args to py.test like:

    tox -e py27 -- py.test --pdb --durations=10 tests/test_connection.py

or even execute a totally different command like:

    tox -e py27 -- pip freeze

By default, it simply calls `py.test`, as it did before.

KushalP/serfclient-py,charleswhchan/serfclient-py