Remove genetic algorithms.

I decided to remove this module for the following reasons: the module
does not quite fit the package's thematic, has references to scipy.ga
(which has been removed) and there are already some great genetic
algorithm frameworks in Python.

This thread discussed the removal:
http://mail.scipy.org/pipermail/scipy-dev/2010-January/013705.html

git-svn-id: https://scikit-learn.svn.sourceforge.net/svnroot/scikit-learn/trunk@365 22fbfee3-77ab-4535-9bad-27d1bd3bc7d8