Save visualizations

[TaiWilkin]

Overview

Users are able to click 'save' while on the visualizations page, and store their currently selected geographies/questions/etc. into local storage.

Data is stored in an array of objects, with each object containing a title and the information needed to recreate the visualization.

The stored visualization does NOT include the survey data, which means that we don't capture stale state data if the dataset changes. However, when completing the follow-up UI tasks we will need to gracefully handle cases where a persisted question or geography is no longer available.

Connects #19

Demo

Testing Instructions

• Select geographies and questions, then click 'save' on the visualizations page.
• View Redux state and local storage and confirm that the visualization data has been added.
• Add additional visualizations and confirm they are added.
• Refresh the page and ensure the visualizations are loaded into state.

[TaiWilkin]

Added a visual "save success" state to the save button. Thanks!