R1:2d7abfd9fa9a

Use HTTPS, not HTTP, in install scripts

Summary:
Via HackerOne. A researcher correctly reports that our install scripts use `HTTP`, not `HTTPS`, to fetch resources and execute them as `root`, which is a potentially significant vulnerability.

Instead, use `HTTPS`.

Test Plan: Verified that these URIs function correctly over `HTTPS`.

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D16958