move .image-caption into base.less for us on homepage, content pages
add .image-caption.overlay style to base.less for us on landing pages
move #hero-image into base.less, add styles from margin-bottom-20
Merge branch 'master' of https://github.com/SU-UComm/bootstrap

# By Scott Stocker
# Via Scott Stocker
* 'master' of https://github.com/SU-UComm/bootstrap:
  additional adjustments to hometop / feature-banner positioning and color.
  fix alignment of hometop / feature-banner in mobile view.