Change default git repo URL to https

Change default git repo URL to https

Since we now support the server side handler for git over https (so
we're no longer using the "dumb protocol"), make https the primary
choice for cloning the repository, and the git protocol the secondary
choice.

In passing, also change the links to git-scm.com from http to https.

Reviewed by Stefan Kaltenbrunner and David G.  Johnston