Extract admin login in features
Let admins send intro/closure mails via web

The emails are sent using ActiveJob (though this is not configured to do
any background processing yet).

We're using activejob_backport as Rails 4.2.0 is not yet released, and
not all of our gems are compatible with the beta.
Add confirm pop-ups on significant admin actions
Make admin log out button fit in header
Move localisation of pages to separate file
Localise admin UI
Localise user create/edit buttons
Revert "Add confirm pop-ups on significant admin actions"

The confirm dialogs are appearing twice (some Rails bug?) and impeding
normal operation.

This reverts commit 26ade37d2b8b3763d607a5e621b8204496671c6d.
Redirect from / to somewhere useful

For logged-in users.
Extract remaining email sending

This provides symmetry with Introduction and FeedbackRequest and keeps
token generation out of the main activity flow.
Move all email sending into jobs
Move modules in app/models into concerns

They don't have the full behaviour of concerns, but it seems like a
better home for them.
Remove module that's only used once

It's simpler and shorter inline.
Add CSV instructions on admin page
Slightly improve look of admin page

More space and horizontal rules make it quite a bit nicer.
Merge branch 'master' into admin-password-reset