Add configuration to deploy to staging

Closes #9

See merge request !11

Trigger a pipeline in the deployment repo when commits land in master
which cause a deployment to the staging instance.

Closes #9

Add ToS link to webapp

Closes #6

See merge request !10

Update legalese at bottom to include a link to the toolkit site.

Closes #6

When the test suite is run we create some mock users. The ucamlookup
application registers signal handlers for the user objects which try to
call the Lookup API when run. To avoid calling external APIs when tests
run, disable the ucamlookup application when running tests.

The demo.raven site should no longer be used. Use "true" Raven Legacy
throughout.

The UCAMLOOKUP_{...} settings were already supported by the webapp
itself but no matching infrastructure had been created around the
various ./compose.sh environments.

Port externalsettings infrastructure

Closes #7

See merge request !9

For Cloud hosting, we'll need this.

We don't actually test serving the frontend but if/when we do, make sure
that the frontend build directory is known to tox.

No changes are required to move to Django 2.2 so do so.

requirements/docket.txt explicitly does not install base.txt but only
includes requirements which *override* those in base.txt. As such, we
need to install base.txt in requirements.txt.

Rather than having DEBUG default to True and setting in in the
production settings to False, have it fail safe and default to Fale
unless set otherwise.

The COMPOSE_ARGS=... recipe in the README for running tox with a mounted
data directory did not work since the tox container's entrypoint was not
set to "sh -c" by default. Fix this which allows arguments to be passed
to the tox command as outlined in the README.

Replace the existing explicit environment-variable based loading of
secrets with the new externalsettings method. Rather than setting a load
of environment variables in the development containers, we add a
settings document inside the container and specify its location via an
EXTRA_SETTINGS_URLS environment variable.

The means that the same mechanism to load settings in development is
used in production and so failure to add settings to
{required,optional}_settings will be caught early.

Tox has been updated to support the new way of setting values.

Create pipeline number and "latest" tags when building

Closes #5

See merge request !8

add GitLab CI configuration

Closes #2

See merge request !7

Add a basic GitLab CI configuration which pull in the AutoDevOps
template and our tox customisations.

Implement frontend UI

See merge request !6

Use the various dialog components to provide implementations for the
index page and a page listing user preferences.

Add a component which can be used to update or create a preference for a
user. It takes the current user's profile and, optionally, their
existing preference. It provides a UI for the UpdatePreference
component's functionality.

Add a component which can be used to show an existing preference for a
user or that a user has no preference.

Add a component which provides a UI to be used in place of the new
preference UI when the user is not signed in. This UI gives details on
the purpose of the application and provides a "sign in" button.

Add a component which can be used in a PagePaper component to indicate
that data is being loaded.

Add a very simple component which is used to space out elements of the
UI.

Add a common set of components used for rendering pages and their
content. The Page component provides the basic layout of the page and
the PagePaper component provides a Paper component where the page
content can be rendered. On small-screen devices, the PagePaper
component expands to full-screen.

Add a component which can be used to update the current preference for a
user. It provides a "draft" preference which can be modified via a
function passed to its children. When this preference is ready to be
submitted, children may update the preference via another function
passed to them.

Add a new component which wraps the preference list API endpoint,
merges all pages of results and passes the result list to its child.

As with our other frontends, we have a "ProfileProvider" component which
fetches the current user's profile and a "ProfileConsumer" component
which other components can use to obtain the current user profile.

Add ProfileProvider to the index page so that all rendered components
have the option of retrieving the current profile.

Add a module which allows calling the backend's API. This is heavily
based on similar API modules from the media platform and PI dashboard.

The dateformat library can be used to format dates in JavaScript in a
more friendly manner than raw JavaScript. Add the library and update
package.lock.

Add configuration to serve the frontend and to build it automatically in
development. Update the Dockerfile to serve the frontend in production.

Add an empty ui application and Typescript frontend. The ui application
serves a single URL, the index page.

Instead of re-directing the user to Raven after logout, re-direct them
to the index page of the application.