Merge branch 'pr/Husseinfo/307'

prevent redirect to other domains.

If cookie.domain is set to blah.com, and a redirect url is provided
as blah.com.my.custom.domain then vouch will reject it and not send
the user back to the incorrect domain.

Merge branch 'pr/martindb/298'

Merge branch 'pr/airbornemint/296'

vouch#266 add cookie.domain when allowAllUsers: true

fix vouch#290 add Azure AD

fix vouch#289 allow `rd`param to support Nginx Ingress

Merge branch 'master' of github.com:vouch/vouch-proxy

vouch#282 error out after six failed login attempts

Squashed commit of the following:

commit a3e33f9
Merge: 0ea425f 054bff3
Author: Benjamin Foote <git@bnf.net>
Date:   Thu Jun 25 13:44:23 2020 -0700

    Merge branch 'master' into pr/yaws-k/279

commit 0ea425f
Author: Benjamin Foote <git@bnf.net>
Date:   Thu Jun 25 13:44:12 2020 -0700

    vouch#266 clarify protected domain

commit 2b68660
Author: Yosuke Kato <55400564+yaws-k@users.noreply.github.com>
Date:   Sun Jun 14 14:27:22 2020 +0900

    Add vouch.cookie.domain description to allAllUsers configuration.