message: Update RHEL and CentOS to latest versions
diff: "CentOS":{
  "publisher":"OpenLogic",
  "offer":"CentOS",
  - "sku":"7.3",
  + "sku":"7.5",
  "version":"latest"
  },
  "CoreOS":{
  "RHEL":{
  "publisher":"RedHat",
  "offer":"RHEL",
  - "sku":"7.3",
  + "sku":"7-RAW",
  "version":"latest"
  },
  "SLES":{
  