They used to be sorted by the code which was not helpful

fixes #8806
requires deploy of new design docs to the platform

Production instances are getting cluttered with invites from
test accounts. Instead of marking them as used we will now completely
remove them.

refers to #8804
refers to #8807\

On a failed login the warden failure app gets called.
Some of the params are changed accordingly but controller
and action remain.
set_locale would detect there was no locale in the path
and thus attempt to redirect. However the params still
belong to the previous request which was a POST to
  Api::SessionsController.
This route does not respond to get requests and so it
would trigger a 404 in production and a 500 in development.

This commit prevents set_locale to act upon warden failure
app controller calls by adding /new to the list of
`NON_LOCALE_PATHS`. (The path is updated by warden to the
name of the action called in the failure app).

A test is included in this commit that tries to login
with an invalid username, password combination and a german
locale set.

fixes #8805

fixes #8794

Reported the underlying issue here:
https://github.com/rails/sass-rails/issues/406

Basically `@import` works like this:
* look for the file relative to the current file
* look for the file as an absolute path following the priorities in the
* asset load_paths

If the file can be imported as a relative path that will take
precedence.

So in order to pick up the head and tails inside customization rather
than in app/assets there are three possibilities:
1) use an absolute path. This is not as easy as it seems. There is no
way of indicating a path is meant to be absolute so we would have to
ensure it does not resolve to a relative path.
2) have a application.scss file inside the customization folder. Since
this is the main file it will be used instead of the app/assets one. In
there relative paths will now also default to the customization folder
rather than app/assets. Once we are in an app/assets file though it will
not go back to picking up customization with relative paths
3) use //= require instead of import. rails-sass advices against this as
each required file would be compiled on it's own and variables could not
be shared.

Going with option 1 here:
```scss
// application.scss:
@import "custom/head_import";
```

```scss
// custom/head_import.scss:
@import "head";
```

As long as there is no custom/head.scss in app/assets it will import
head as an absolute path and thus prefer config/custom over app/assets.

This seems like the best option for now as it does not require changes
to the deployments.

We now use the hash of the token for comparison and as the id.
In order to use it you need the original token though. So forms and
thus the session should have token.to_s rather than token.id.

only use the <pre> tag if the response was a text message i.e. during dev errors.
Use the alert-danger class of bootstrap 3 rather than alert-error.