add sections and restructure page

[cnell-usgs]

Changes made:

App restructured to use nested components that are composed in Visualization.vue, added sections "What's new" and "About" and set up responsive grid. Minimal theme styling. Adds scroll to navigation to menu bar, although when running locally this seems to shift the entire page left into the margins?

Testing:

Before making this pull request, I:

• [ ] Cleaned the code the way Vue likes it - run 'npm run lint --fix'
• [ ] Made sure all tests run
• [ ] Ran WAVE plugin 508 compliance tool

I can confirm this has been checked on:

• [ ] Chrome
• [ ] Safari
• [ ] Edge
• [ ] Firefox
• [ ] Samsung Internet
• [ ] Internet Explorer 11 (not supported, but still needs at least a working user redirect page)

[cnell-usgs]

Solved several problems I was stuck on, thanks!