Update README
Update README

Updates HOW-TO run packstack from source.

Change-Id: I8e025775b963d09b2a77ba6eaf57340761f43de8

fr34k8/packstack,mahak/packstack,fr34k8/packstack,imcsk8/packstack,mahak/packstack,imcsk8/packstack,openstack/packstack,stackforge/packstack,xbezdick/packstack,stackforge/packstack,openstack/packstack,openstack/packstack,xbezdick/packstack,imcsk8/packstack,stackforge/packstack,fr34k8/packstack,mahak/packstack,xbezdick/packstack