Remember map extent #50 [Added functionality]

[harsh5902]

Closes #50

🛠️ Fixes Issue

used localstorage of the user to remember the mapextent

👨‍💻 Changes proposed

If user moves his/her pointer on the map and moves to new location then localstorage will store his session and next time when he/she starts the app will get the same location where they left before.

You can see the center latitude and longitude on the developer tools application tab

📷 Screenshots

[harsh5902]

Sure I will make the necessary changes as needed

[harsh5902]

@nilsnolde I have made the necessary changes you pointed out and also used localstorage for zoom level as well

[nilsnolde]

LGTM, thanks!