redo main page

[daveaseeman]

• create unique header for homepage
• move intro.md to that header
• remove personal info & shorten intro.md
• make homepage header full-screen
• add arrow down with anchor tag
• make site title's border around a span tag
• add image to background w/ overlay (change later to gif/video)
• fix instafeed (only get most recent image from array)
• remove home-page link from homepage header

...

• rethink header on other pages