Ensure LDAP provided email is always compared case-insensitively.
Created by: patthoyts
LDAP databases may store email addresses in mixed case so ensure we only work with a lower case version to avoid missing a valid account after LDAP login.
[PT: this commit resolves github issue #455 (closed)]
Signed-off-by: Pat Thoyts patthoyts@users.sourceforge.net