- Added "Learn More..." and "Quick Links" sections
- Removed "NANOGrav On Tour" section (will be migrated into new section)
- Created "Recent News" section and put Portfolio Review Response in it
- Organized HTML
Merge remote-tracking branch 'origin/develop'

Conflicts:
	index.html
Made some layout changes to homepage and added content to astronomers,
people, institutions, and PIRE sections.
New layout, revising text.
Added new content, re-organized directory structure, improved layout, improved readability.
Changes to index
Merge branch 'master' of https://github.com/ryanslynch/nano-web into develop

Conflicts:
	index.html
	participants.html
Merged Ryan's changes, updated social media links