chore(Dockerfile): Fix packer url. (spinnaker#264)

fix(manifest): Fix using base64 artifacts in manifest bakery

chore(build): Gradle 4.7

chore(packer) - upgrade packer binary to 1.2.2 (spinnaker#244)

The addition of spot changed the defaults, swap them back (spinnaker#235

)

- Change the spotPrice default in the virtualizationSettings to 0
  instead of auto. Set to auto it was defaulting to doing bakes using
  spot, which is a big change from the way we have been operating.
- Need to quote the spot price in the templates, otherwise packer throws
  an error with "expected type 'string', got unconvertible type 'float64'"
- Leave the spotPriceAutoProduct set in the virtualization settings, so
  users can set just aws_spot_price in their bake stage and have it work
  as expected.

The addition of spot changed the defaults, swap them back (spinnaker#235

)

- Change the spotPrice default in the virtualizationSettings to 0
  instead of auto. Set to auto it was defaulting to doing bakes using
  spot, which is a big change from the way we have been operating.
- Need to quote the spot price in the templates, otherwise packer throws
  an error with "expected type 'string', got unconvertible type 'float64'"
- Leave the spotPriceAutoProduct set in the virtualization settings, so
  users can set just aws_spot_price in their bake stage and have it work
  as expected.

feat(bake) Added AWS spot pricing configuration when baking AMI's. De…

…faults to 'auto'. (spinnaker#232)

feat(bake) Added AWS spot pricing configuration when baking AMI's. De…

…faults to 'auto'. (spinnaker#232)

chore(config):updated ami id's for baseImage (spinnaker#231)

fix(rosco) Fix aws enhanced_networking backwards incompatibilities (s…

…pinnaker#227)