More resilient Cloudbreak Upscale/Downscale

Features

• Allow Cloudbreak to perform pre/post recipe salt sates only in newly created nodes.
• Allow Cloudbreak to perform post cluster install only recently created nodes

Bug fixes

• Duplicate entries in hostmetadata should no longer cause upscale/downscale request to fail
• Downscale AWS request should be batch at 20 instances at a time (detach/terminate limits)