swc-windows-installer.py: Rename ~/.nanorc to ~/nano.rc

The nano FAQ hints that this is the prefered path on MS Windows [1],
and Ethan White confirmed it in testing [2].

[1]: http://www.nano-editor.org/dist/v2.2/faq.html#3.9.1
[2]: https://github.com/swcarpentry/bc/pull/357#issuecomment-37482899
swc-windows-installer.py: Use '~' in ~/nano.rc includes

On Wed, Mar 12, 2014 at 04:44:31PM -0700, Ethan White wrote [1]:
> Got it. We just need to change the `/c/Users/River/` in the include
> statements to `~/` and everything works great!

[1]: https://github.com/swcarpentry/bc/pull/357#issuecomment-37483149
Merge branch 'python' into bc-namespaced-python

* python:
  swc-windows-installer.py: Use '~' in ~/nano.rc includes
  swc-windows-installer.py: Rename ~/.nanorc to ~/nano.rc