Fixed style regression

[noisecapella]

What are the relevant tickets?

Fixes #620

What's this PR do?

Moves the react-mdl CSS back into dashboard.js. It overrides many common style rules which is why we're seeing different styles with it included. We're only using bootstrap CSS on the 404 page currently so this shouldn't cause any problems.

How should this be manually tested?

First, turn on DEBUG mode so we can view the 404 page. You can do this by setting DEBUG=False in settings.py and adding your host name to the ALLOWED_HOSTS list.

Then run NODE_ENV=production ./webpack_if_prod.sh in your terminal to generate static assets. Next, run docker-compose run web ./manage.py collectstatic to copy static assets into staticfiles/.

After that, look at the two screenshots for the program page in #620. Go to a program page and verify that it looks like it did before, more or less. Go to /xyz/ and verify the 404 page still works as expected, and also click the dropdown and click 'logout' to make sure that works.

[giocalitri]

@noisecapella just FYI, at the addresses /404/ and /500/ you can see the error pages with DEBUG=True

[giocalitri]

👍