Deploy across an entire web cluster

Adds deploy, undeploy, and redeployAll to webapp cluster entities (DWAC and ControlledDWAC).

Also fixes some issues noticed in how tasks are tracked and displayed.
For the future... would be nice to not block here if a new cluster member's VM is starting up. Ideally we'd only block for nodes where this method does the deploy. For those that have yet to pick up the `WARS_BY_CONTEXT` config then we could just rely on its `start()` to do it. But that sounds tricky.