add ONBOOT and NM_CONTROLLED to redhat/network_static

Fixes private networking on Centos 6. It seems using Network Manager (NM_CONTROLLED) to change an interface while running is a bad idea. I'm not sure of any specifics though. This is the only way I could get it to work.
Merge pull request #2605 from teaforthecat/patch-1

guests/redhat: add ONBOOT and NM_CONTROLLED to redhat/network_static