Dropbox changes.
Changed name and location of thumbnail files.
Added a helper method to retrieve the thumbnail image for a donor based on name.
Revert recent changes to workshop signup form.
Created HTML elements using a loop and database query rather than hardcoding.
Made JS behavior more abstract to accommodate any number of donors properly.
Merge branch 'staging' of https://github.com/code-dot-org/code-dot-org into donor_slider

Merging donor_slider into staging
Changed interval and added fadeIn/fadeOut. Removed unused variable.
Changed default display style.
Added slider to bottom of homepage.