0.4 doc updates

Proofed the entire Aperture Tiles site to clean up formatting and fix outdated references to code.

Still have a few things to add:

- [x] Reconcile outdated Client-Side Rendering code block on the Docs > Development > Configuration page
- [x] Update Docs > Development > Quick Start and Generation pages to replace outdated spark-run script information 
- [x] Pull in latest changes to API docs
- [x] Update links on Download page for new packaged distributions
- [x] Update screenshots in User Guide, if time allows