Optionally add parameters to the /login redirect to support organization member invitations

[jekennedy]

When users are invited to join an organization they receive an invitation link by email. This link redirects them to the configured default login route with invitation-specific parameters appended (see below). The problem is that the express-openid-connect module does not include these parameters on the redirect url. The proposed code change resolves this issue.

The following parameters are now (optionally) included on the default login url:
invitation
organization
organization_name

[frederikprijck]

Thanks for the contribution.

This is an Open ID Connect SDK, Organizations is an Auth0 feature so we can not support this natively, see #365 for how to implement it.