Save zoom level

[nstjean]

Fixes #373

I've added a zoom tag of zoom:xx to the data being saved.

I've also added package.json update because this requires leaflet-blurred-location version 1.4.1 to work.

[welcome]

Thanks for opening this pull request! This space is protected by our Code of Conduct - and we're here to help.
Please make sure you've bumped up the version number in the repository's package.json file and that you've incorporated your changes in the /dist/ sub-directory.
Dangerbot will test out your code and reply in a bit with some pointers and requests.
Also please refer here for installation help 💿
There may be some errors, but don't worry! We'll work through them with you! 👍🎉😄
It would be great if you can tell us your Twitter handle so we can thank you properly?

[welcome]

Congrats on merging your first pull request! 🙌🎉⚡️
Your code will likely be published to PublicLab.org in the next few days. In the meantime, can you tell us your Twitter handle so we can thank you properly?
Do join our weekly check-in to share your this week goal and the awesome work you did 😃.
Reach out to someone else working on theirs on Public Lab's code welcome page. Thanks!
Now that you've completed this, you can help someone else take their first step!
See: Public Lab's coding community!

Help others take their first step

Now that you've merged your first pull request, you're the perfect person to help someone else out with this challenging first step. 🙌

https://code.publiclab.org

Try looking at this list of `first-timers-only` issues, and see if someone else is waiting for feedback, or even stuck! 😕

People often get stuck at the same steps, so you might be able to help someone get unstuck, or help lead them to some documentation that'd help. Reach out and be encouraging and friendly! 😄 🎉

Read about how to help support another newcomer here, or find other ways to offer mutual support here.

[jywarren]

Awesome. Should we republish on NPM?