Cypress failure for maintenance mode isn't clear

[oudeismetis]

Cypress is designed to stay in a failure state until it's able to run against the latest version of the code deployed on Heroku.
There error given in that failure state isn't clear:

We should show a custom error instead and say something like:

If this error just happened, wait a few minutes as the Heroku deployment likely hasn't finished yet.
This test will automatically re-run when the app is ready to be tested.

If this error has been here for more than a few minute, check Heroku.
There was likely an error while building/deploying the application.

[oudeismetis]

Resolved by #150