Support for specifying `serviceAccount`

[surajssd]

Some applications that were deployed needed some special access like talking to kubernetes API server. And hence I found this to be present in lot of configuration with different value.

$ kubectl explain deployment.spec.template.spec.serviceAccountName                      
FIELD: serviceAccountName <string>

DESCRIPTION:
     ServiceAccountName is the name of the ServiceAccount to use to run this
     pod. More info: http://releases.k8s.io/HEAD/docs/design/service_accounts.md

Docs about this, and API reference.