Make apache restarts a little more forgiving

Apache sometimes is slow to release the port (from the kernel's
perspective) which can cause restarts of apache to fail due to the
requested port already being bound. This fix introduces a small sleep
between the stop and start to help make apache deployments a bit
more resilient.

Change-Id: I9697d71f3cb2d8d5da8fe7ffa8b3e1ade9d52afd
Closes-Bug: #1342256
Merge "Make apache restarts a little more forgiving"
Merge branch 'master' of github.com:openstack-dev/devstack