The `buildPython*` function computes name from `pname` and `version`.
This change removes `name` attribute from all expressions in
`pkgs/development/python-modules`.
While at it, some other minor changes were made as well, such as
replacing `fetchurl` calls with `fetchPypi`.
We have two derivations, one that supports Cuda, and one that does not.
The names, TheanoWithCuda and TheanoWithoutCuda, now reflect that.
Furthermore, a boolean passthru.cudaSupport was added.
In the future the two derivations should be merged in one, with a
parameter `cudaSupport`.
