Handle https requests

[eniklas]

Some browsers default to https, or users mistakenly type it in the URL. Redirect those requests to http, or support https if you can do it without browsers screaming about self-signed certs and such. If https can be supported nicely, http should redirect to it instead of vice versa.

Update the docs too, we'll need to open port 443 on the router.

[eniklas]

See https://github.com/GoogleCloudPlatform/flask-talisman.