* Fix client-side username validation at registration

It used the Account::USERNAME_RE regexp which is for *remote* users,
local user validation is stricter. Also take into account max username length.

* Add client-side form validation for password change

* Add client-side form validation to dedicated registration form

Previous changes only applied to the /about page, not the dedicated form on
/auth

* Verify link ownership with rel="me"

* Add explanation about verification to UI

* Perform link verifications

* Add click-to-copy widget for verification HTML

* Redesign edit profile page

* Redesign forms

* Improve responsive design of settings pages

* Restore landing page sign-up form

* Fix typo

* Support <link> tags, add spec

* Fix links not being verified on first discovery and passive updates

* Fix password recovery

* Use “resource” instead of “current_user”

* add pam support, without extra column

* bugfixes for pam login

* document options

* fix code style

* fix codestyle

* fix tests

* don't call remember_me without password

* fix codestyle

* improve checks for pam usage (should fix tests)

* fix remember_me part 1

* add remember_token column because :rememberable requires either a password or this column.

* migrate db for remember_token

* move pam_authentication to the right place, fix logic bug in edit.html.haml

* fix tests

* fix pam authentication, improve username lookup, add comment

* valid? is sometimes not honored, return nil instead trying to authenticate with pam

* update devise_pam_authenticatable2 and adjust code. Fixes sideeffects observed in tests

* update devise_pam_authenticatable gem, fixes for codeconventions, fix finding user

* codeconvention fixes

* code convention fixes

* fix idention

* update dependency, explicit conflict check

* fix disabled password updates if in pam mode

* fix check password if password is present, fix templates

* block registration if account is maintained by pam

* Revert "block registration if account is maintained by pam"

This reverts commit 8e7a083d65.

* fix identation error introduced by rebase

* block usernames maintained by pam

* document pam settings better

* fix code style

* Fix autocomplete in two_factor.html.haml

* Fix autocomplete in registrations edit.html.haml

* Fix autocomplete in passwords edit.html.haml

* Fix autocomplete in _registration.html.haml

* Fix autocomplete in new.html.haml

* Fix autocomplete in show.html.haml

* Add autocomplete option to sessions new.html.haml

* Add autocomplete option to 2FA new.html.haml

* Add autocomplete option to 2FA show.html.haml

* add haml_lint to Gemfile

* add .haml-lint.yml

* fix warnings of haml_lint