Added new images and removed old images

After thinking about it most of the day today, I decided to change the
subject of the site to be about Neil Armstrong. So all new images have
been sourced from wikipedia, and from the Apple desktop backgrounds.
Updated main content component styles

· Changed the opacity of the navbar background, and style the link
colors and hover.
· Changed the header background.
· Added a background to the intro section.
· Added the twitter styles.
· Updated the article display and style.
· Changed the footer background color.
Updated content and added embedded twitter plugin