update copyright info, URL
don't require libsvm-dev to build

scikit-learn ships a modified LIBSVM. Also removed the patch to use
system LIBSVM, which is not going to work anyway (it wasn't used).
require Cython 0.20.1 to build Debian package

Older versions are going to give trouble, esp. with Python 3.x.
require ATLAS at build time

This should enable building with the system-wide ATLAS instead
of the partial version shipped by scikit-learn, which contains
reference implementations of BLAS algorithms.