fix(case-sensitivity): support devise case_insensitive_keys for session ...

...and password controllers

see also: https://github.com/plataformatec/devise/wiki/How-To:-Use-case-insensitive-emails

Prior to this, email would always have to match case exactly, regardless of any underlying devise configuration settings.

The spec diff looks worse than it is. Added a new nested describe block to test 200 vs 400 status codes without altering the before setup of the other specs.