Managing states during polling (lookup.ts)

[pmilano1]

I submitted a PR to add smartthings functionality - https://github.com/jef/streetmerchant/pull/1902/files

What I wanted to do, is apply a state timer to the solution, but I couldn't find the proper place to do so except for directly in lookup.ts. I'm not sure if there is a better place. It would look like this -

• New env var 'SMARTTHINGS_SWITCH_DURATION' (int/seconds)
• if 'SMARTTHINGS_SWITCH_DURATION' since last 'in stock', turn off switch

Thoughts?