Switch from using the git protocol to https for pip requirements

The current URL for pip requirements in Tuskar requires that
web proxies allow the "git" protocol to install the pypi
package.

This patch replaces that with a read-only checkout via https to
walk through the proxies and download regardless of connection
type.

Change-Id: Ie1f8ef1c47f09c00d2f951c6062a929d1b84c7b5
Merge "Switch from using the git protocol to https for pip requirements"