Sets up and enables NetworkManager.
In testing this was the only way to get the network to come up after
reboots on centos.
Change-Id: Iac8d982977982d886b29a8933b59dd3f55578769
Add the slow-network element which defaults the timeout of network
bring-up to 60 seconds set by the NETWORK_TIMEOUT environment variable.
Syncs the ops repository to a known location so that we can use the
element when building images.
Rename the register-images script to register-nodes as that what it
actually does.
Change-Id: I403667f7bf6c69e255a4f5639ee4a8e0e8af18e3