- adjusted elements to fit the pixel grid for better scaling
- optimized the PNG asset and the SVG asset

* Basic onboarding modal that's shown to users once

* Lay out pages 2 through 5, add images, style modals (#1509)

* Lay out pages 2 through 5

Added images and laid out pages 2 through 5 in the jsx file. SCSS will
come, still working on just seeing if this works at all.

* Fix jsx errors, add images to modal pages, style modal pages

* Add animations to onboarding pager changes, improve wording and styling

* Finishing touches on the onboarding

* Add missing propTypes

* Update wording

* vector (svg) logo with correct inner shape and colors

* minimized svg logo

Fixed the nasty banding & recompressed it at about the same level

Reduced by running through `guetzli` image optimizer.

registration API

Mostly resolves #8, though attachments are still not displayed in public view