update readme as xip.io becomes bosh-lite.com
update readme as xip.io becomes bosh-lite.com

Signed-off-by: Connor Braa <e624947c8d30070ca3f5f65daa9bdf76de21947b@pivotal.io>

cloudfoundry-incubator/docker-registry-acceptance-tests,cloudfoundry-incubator/docker-cache-acceptance-tests,cloudfoundry-incubator/docker-registry-acceptance-tests,cloudfoundry-incubator/docker-cache-acceptance-tests