Make check no longer exists, update releasing docs.
Releasing steps
===============
-* Run ``make check``, ``python3 setup.py nosetests``, ``python2 setup.py nosetests``
+* Run ``python3 setup.py nosetests``, ``python2 setup.py nosetests``
* Update version number in ``setup.py`` and ``CHANGES.rst``
* ``git commit -m "Preparing ${VERSION}"``
* ``git tag -as ${VERSION}``
