live pipeline view

[vbehar]

following up on #72, it would be great to have a "live" view of a running pipeline: auto-reload the pipeline information.

we could either:

• use a new eventSource to push the pipeline in json format each time it's updated
• or use the new /org/repo/branch/build.yaml endpoint to retrieve the pipeline in YAML. if you prefer we can also add a new endpoint to retrieve the JSON representation of a pipeline. and then periodically retrieve the pipeline from this endpoint

and use this information to display:

• timings for recently completed steps
• ...

[jrx-sjg]

This is a huge +1