Use nosetest for testing.

Make tests confirm with the NumPy testing guidelines.

Fix also references to objects that have changed name and use relative
imports wherever possible.

Disable for now tests that are causing problems.

See http://projects.scipy.org/numpy/wiki/TestingGuidelines for more info.

From: Fabian Pedregosa <fabian@fseoane.net>

git-svn-id: https://scikit-learn.svn.sourceforge.net/svnroot/scikit-learn/trunk@320 22fbfee3-77ab-4535-9bad-27d1bd3bc7d8