Explorer should be a Vue App

[vforgione]

Server side rendering worked well for the POC phase of the app. To get a really slick user experience we should use Vue.

• Vue and Phoenix work well together, once you get them in their places
• Bring maps under Vue
• Ability to search, select a data set, and view it
• Bring charts under Vue (also consider alternatives to chartjs)
• Ability to search, select a data set, and download records that match search
• Ability to select multiple data sets and compare their data
• Ability to select multiple data sets and overlay geographic data on a map (use a shapefile data set to display or refine a query)

Epic #370