RemoteAuth EZProxy CGI authentication

RemoteAuth EZProxy CGI authentication

This commit adds a RemoteAuth handler (and associated templates,
configuration, and sample data) for EZProxy CGI user authentication:

https://help.oclc.org/Library_Management/EZproxy/Authenticate_users/EZproxy_authentication_methods/CGI_authentication

The user is presented with a login form.  If their account is
authorized, they will be redirected to EZProxy with a valid
authentication ticket, allowing them to access online resources.  If
they are not authorized, an error message is displayed indicating why
the auth attempt failed.  The login form and error messages use
Template Toolkit (TT2) templates and can be customized.

Signed-off-by: Jeff Davis <jeff.davis@bc.libraries.coop>
Signed-off-by: Jane Sandberg <sandbej@linnbenton.edu>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>