DOC: update release instructions for script tests

I needed to change the automated script tests in nibabel to accomodate
the script tests in nipy.
DOC: update surrogate array docs / docstrings

The API seems to have changed a little; update imports and
documentation  Fix docstrings for sphinx errors.
DOC: minor rejigging of enn doc / docstrings

There were confusing sphinx errors for the ``enn.rst`` file.  Some were
solved by upgrading Sphinx from 1.0.3 to 1.1.3; the docstring edit
solved a couple of indentation errors.
DOC: updating doctests sphinx docs

Doctests are all now passing on my box, but with some extra changes in
the code, that I will submit as a separate pull request. Basically I
needed to allow objects for coordinate map coordinate types to allow the
sympy things that Jonathan is doing in the long coordinate map
discussion.