Standalone API server with integration tests

[wallrj]

• Tried to separate out the API server options that require kubernetes API configuration options.
• Don't apply those command line options if --standalone-mode has been supplied.
• Added a wrapper around the Kubernetes integration test framework to also launch the Navigator API server and connect it to the same Etcd server.
• Currently parses stderr to check for a successful startup message, but the API server ought to have an /healthz endpoint.

Fixes: #364

Release note:

NONE

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[jetstack-bot]

@wallrj: PR needs rebase.

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