Concourse deployment of cf-abacus

[mogul]

In order for the cloud.gov team to operate and iterate on the abacus service, we need to capture knowledge about how it is deployed, secured, operated, etc. and automate the deployment for future.

Acceptance Criteria

• [ ] There's a cg-deploy-abacus GitHub repository that is actively "flying" in Concourse
• [ ] docs.cloud.gov's contributing section includes any necessary operations notes

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Background that could help:

• Review Dan's trail of breadcrumbs from when he brought our deployment to its current state; see in particular the comments thread.
• Some notes on scaling from a while back

[mogul]

The upstream abacus repo now provides Concourse pipelines.

[mogul]

Icebox'ing for now; will look at it again once we've got Diego deployed.