swc-windows-installer.py: Restore nose entry point

swc-windows-installer.py: Restore nose entry point

This restores the nose entry point which was removed in 94caead
(swc-windows-installer.py: Remove IPython and nose entry points,
2013-10-21).

On Tue, Oct 22, 2013 at 11:36:21AM -0700, Ethan White wrote:
> IPython works fine for me on Windows 7 for both Anaconda and Canopy
> with no added entry points needed.
>
> Nosetests does not appear to have an entry point on Anaconda and I
> forgot to test it with Canopy.

I used a slightly different bin path than we'd used previously, to
respect 806fedf (swc-windows-installer.py: Rework install paths to use
~/.swc, 2013-10-21).