Fix curl commands

Sometime apparently very recently, Github changed the hostname for grabbing content from projects from `raw.github.com` to `raw.githubusercontent.com`.

This broke the `curl` commands in use in the docs because they did not use `-L` to follow redirects. Images continue to work because the browser will chase the redirect.

Rather than fix the hostname everywhere, which isn't a bad idea, I just added `-L` to all invocations of `curl`.

(Looks like vim added an end of line to the end of `quick-start.md` as well.)