Refactor promote and publish boxes

Signed-off-by: Andrei Dinin <adinin@pivotal.io>
Update VBoxGuestAdditions to 4.3.18

Signed-off-by: Andrei Dinin <adinin@pivotal.io>
Update publish-stemcells for GoCD

* Move from pipeline bucket to final bucket instead of uploading

Signed-off-by: Andrei Dinin <adinin@pivotal.io>
Split publishing boxes and promotion

Signed-off-by: Andrei Dinin <adinin@pivotal.io>
Update cloudfront and bucket

Signed-off-by: Andrei Dinin <adinin@pivotal.io>
Update location of packer-bosh.tgz

Signed-off-by: Andrei Dinin <adinin@pivotal.io>
WIP1

* Remove releasing for testing purposes

Signed-off-by: Andrei Dinin <adinin@pivotal.io>