Network installation should be secured by HTTPS

[dannyniu]

In the current doc, network installation command is issued with:

curl http://uwsgi.it/install | bash -s default /tmp/uwsgi

HTTP is the original plaintext version of the application protocol running over the SSL/TLS transport protocol used in HTTPS. HTTPS provides authenticity guarantee in addition to confidentiality, and should be preferred.

Suggested change:

• using the network installer

curl https://uwsgi.it/install | bash -s default /tmp/uwsgi

What's more, the network installation live script URL is having 404 error right now.