Add done attribute to shopping list

[DellanX]

Description

I needed to be able to determine whether or not the item was checked off in Grocy. Thus I mapped the 'done' attribute over from the raw shopping list item.

NOTE: Tox didn't run out of the box correctly for me, I needed to add a comma on line 5 between TRAVIS and TRAVIS_* to get the test suite to run correctly.

Related issue (if applicable): NA

Checklist

• [X] The code change is tested and works locally.
• [X] tests pass. Your PR won't be merged unless tests pass
• [X] There is no commented out code in this PR

[DellanX]

I have a second commit following this one on my branch at: https://github.com/DellanX/pygrocy/tree/feature/annotate-data-models.

I'd like to close this PR before attempting that one, as that PR will fix a bunch of issues cause by null data, and adds None type annotations