setup_panda.sh url in docs is broken again

[mattkiefer]

In the admin prod deployment docs at http://panda.readthedocs.org/en/1.1.1/amazon.html the url to wget the setup_panda.sh shell script is broken.

I think this is due to a change in github url convention -- and not a version number issue. (i.e., this issue is not a dupe of #939)

This url worked instead:
https://raw.githubusercontent.com/pandaproject/panda/master/setup_panda.sh