Replace github with git.openstack.org
Replace github with git.openstack.org

This commit updates the website copy, replacing repository links that
pointed to github.com with git.openstack.org. Since the repos at
github.com are read-only replicas, we should not direct users to
github. There is also danger of these replicas falling out of date in
addition to being fully unsupported.

Change-Id: I1f36c144ccab8e9140f427fcacb82d7812654741

stackforge/apps-catalog,stackforge/apps-catalog,stackforge/apps-catalog,stackforge/apps-catalog