UI/Backend: SSL support

[jecluis]

What needs to be done

The s3gw-ui backend will need to present both the UI (at /), as well as the API (at /api/) with SSL support.

Why it needs to be done

Because security.

Acceptance Criteria

s3gw-ui backend deployment runs on port 443, supporting HTTPS connections, with a user-specified certificate.

Additional Information

This will likely require the SSL certificate to be configurable, most likely via environment variables.

[jecluis]

Pushing this to post v0.23.0, as per the reasoning on #740 :

LH controller deploys the s3gw-ui container in the same pod as the s3gw container, effectively allowing us to do inner-pod communication between the two

and

we can ignore the SSL validity, we can even do plain HTTP, because the traffic should be limited and isolated to the pod.

While of the utmost importance, this will not be required for LH 1.6.