Downcase email addresses from CAS when checking against users table

[sandbergja]

Some users have email addresses in all caps in SSO. This leads to problems when they try to authenticate into CommunityArchive@LBCC.

The best solution would be to open a pull request in https://github.com/nbudin/devise_cas_authenticatable that allows us to downcase these email addresses.

Some notes from the maintainer of that project:

"Normalizing email addresses seems like a useful idea in general (not just for upper/lowercase, but for plus-prefixed segments like [email protected]). devise_cas_authenticatable currently doesn't have a way to handle this, but it certainly could[...] My suggestion would be to add an optional config property (similar to cas_user_identifier) that would accept a proc (or lambda or whatever) that normalizes user identifiers before passing them back to the app."