Add HTTPS support

[willdurand]

Automatic updates require signed firmware but it uses HTTP instead of HTTPS.

I could not make HTTPS work yet. The example in this thread does not work but the fingerprint seems OK. I receive the following error:

HTTP_UPDATE_FAILED Error (6): Update error: ERROR[6]: Stream Read Timeout

There are many issues in GitHub and elsewhere, like this one but I don't know what we could do. An idea would be to try with a local HTTPS server because people reported issues with big SSL certs. I don't know.