MOTOR-28 Don't rely on nose to run setup_package.
MOTOR-28 Import SkipTest from unittest or unittest2, not nose.

I intend to use unittest2's backport in Pyhon 2.6.
MOTOR-28 Use unittest or unittest2, not nose, for "python setup.py test".

synchrotest still uses nose.
No need to include dependencies in tox.ini.