4.8.0

Features

• download-product now supports defining a custom stemcell-version in the config file.
  This flag is --stemcell-version, and requires --stemcell-iaas to be set.
  If --stemcell-version is not set, but stemcell-iaas is set,
  the command will download the latest stemcell for the product.
• bosh-diff now supports the --check flag.
  If set, the command will fail if there are differences returned.
  This resolves issue #488]
• stage-product now accepts a config file to define command line args.
  This matches patterns for automation available in other commands.