Control Repository Builder for Strider CD

Job plugin for Strider CD that:

Invokes Grunt in the root directory of the control repository. The Grunt build should assemble and submit global site assets and inform the content service that a new version of the control repository is available to pull.
Reads a content-repository.json file from the root directory.
Provision a Strider job using the Deconst content plugin for each content repository described there that doesn't already exist.

`content-repositories.json` format

The content-repositories.json file must contain the following JSON:

[
  { "kind": "github", "project": "deconst/deconst-docs" }
]