fixes #6964 - replace default scope that hides users with explicit scope

(cherry picked from commit cad9cce912a371018a489a874d896af241f91bd0)

fixes #3272 - allow 'admin' account to be removed and replaced

fixes #3892 - process REMOTE_USER_GROUP_N and REMOTE_USER_GROUP_#, add user to groups based on external user groups.

fixes #3528 - Populate first name, last name, and email, if available.

Fixes #3753 - always use main_app to determine paths for running an isolated namespace plugin

fixes #3312 - support /users/extlogin as a login page based on REMOTE_USER

fixes #3597 - removing rr gem, make tests consistent by using just mocha

Fixes #3043 - Support Signo on API level using BasicAuth

fixes #2988 - merge authentication code, enables REMOTE_USER auth on new API controllers

Fixes #2722 - Support for crossdomain auth

Newest Signo support authentication across more domains. We just need to
look not only to a cookie but parse parameters for getting username.