Add golang slave image support in pipeline

[hrishin]

In order to support go runtime, the pipeline needs to support the following things

• Jenkins slave image with golang build (golang, dep, glide etc) environment
• Update the spawn config to refer golang slave image with go key mapping
• Check if analytics works fine with go runtime

[sbose78]

Something like this https://github.com/sbose78/osio-pipeline/blob/master/vars/spawn.groovy#L39 ?

[piyush-garg]

Yes @sbose78 that is correct for the second task, only concern, better we use go in spite of golang

For the first task, we need to figure out if there is an upstream image for go