Upgrade to golang-1.8.3 in the docker image pipeline.
Upgrade to golang-1.8.3 in the docker image pipeline.

[#150333287](https://www.pivotaltracker.com/story/show/150333287)

Signed-off-by: Dale Wick <188d987a4b971a1fecf708bf002a3b94c86c96a2@pivotal.io>

barthy1/bosh,barthy1/bosh,barthy1/bosh,barthy1/bosh