IU-LOGIN backends

[skoudoro]

We should add a new authentication backend: IU-LOGIN

More information for adding a backend :

• https://kb.iu.edu/d/atfc
• http://python-social-auth-docs.readthedocs.io/en/latest/backends/implementation.html

[dmreagan]

Unfortunately, there is no Python example in this list. You might think about submitting one if you get it figured out.