Only show the scratchpad when already controlling peripherals
Only show the scratchpad when already controlling peripherals

Putting this behind a prop flag makes it easy to disable this behavior.

Test Plan:

Continue to see "Scratchpad available" [here](http://localhost:9000/testrender.html)

Auditors: michelle

ariabuckles/perseus,learningequality/perseus,ariabuckles/perseus,ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus