Add task persistence

[ryankurte]

Currently tasks are loaded (task-load NAME FILE) then launched dynamically (task-start ARGS). It is desirable to sync the state of these tasks to the device so they can be automatically started on boot.

This probably requires:

• [ ] Storage support (NVS) for task information
• [ ] Checking for stored task(s) at startup
• [ ] task-sync INDEX ARGS command that syncs the current task to disk
• [ ] task-del INDEX ARGS command that removes the current task from disk