add place id to results table in distributed scraping

hi,
i think the `results` table in the seed job db should include the google maps `place_id` to avoid deduplication.

it could be taken even a step further, combining the `place_id` with a `timestamp` in a primary key.

this way a place can be rescraped after some arbitrary amount of time, ensuring updated data and minimizing
scraping twice the same place.

let me know what u think about it.

thanks

mattia papaccioli