coordinate_descent is the exception, since it plays tricks with
X is X_init that I don't fully understand yet.

This reverts commit 59a7b18.

Thanks @ogrisel for noticing.

s/nn/n/ in dictionary and optional

See issue #358:

    #358

When searching or installing scikit-learn with pip or easy_install
the right package name is scikit-learn.

Fix by Brian Holt

Conflicts:

	doc/whats_new.rst

Fixes #395

warning for old version(0.9)