PlanHookStep

[dvallin]

Is your feature request related to a problem? Please describe.
I do not want Spacegun to talk to my Docker Registry (because it do not have one or it has a weird api). Instead I want to call a hook with some image information.

Describe the solution you'd like
A PlanHookStep that receives an image and plans a Deployment with it. This is basically a call to spg run but wit additional json in the post body, that can be interpreted by the pipeline. The pipeline will fail if it is missing.

1. Add an optional Post Body to the run endpoint
2. Parse it in the PlanHookStep and plan a deployment with it