Support multiple tasks (?)

[ryankurte]

Multiple tasks would allow people to compose services on their devices, but, would also require a bunch of work. Unsure if this is extremely useful?

Tasks:

• [ ] Upgrade app_mgr.c to use an array of tasks and to take task name (or index) options
• [ ] Upgrade all hardware managers with FreeRTOS primitives for mutual exclusion to ensure only one task can own a given peripheral at a time