Slideshow aspect ratio.  #1557

New slideshow forms take an aspect ratio option.  It cannot be changed.

Added image styles for each of my ratios.

Added a #process function so I can change the aspect ratio used by image crop.  I've tested that this works, but I still need to figure out and provide the right values here.

Updated the theme to use one of the new image styles.  Still need a better way to figure out the current region's width.
Merge branch 'SCHOLAR-3.x' of github.com:openscholar/openscholar into SCHOLAR-3.x