Wrapper around tox for Wikimedia Jenkins

The Wikiomedia Jenkins jobs invoke tox commands at the root of the
repository and hence expect a tox.ini there.   This patch creates the
basic tox configuration which basically invokes tox under /server/ .  We
could probably move everything at the root of the repository but I did
not want to be too invasive.

List test requirement (nose, coverage) in the new test-requirements.txt
file.

Ignore flake8 error in setup.pyp due to multiprocessing module being
imported but never used.

Configure pep8/flake8 via server/setup.cfg

Change-Id: Ib5d341a8f5cffce906d8b237345c8030607c0905