Backport master
Enhanced Importer

Refactor the slide importer to use a progressbar for progress
notifications. Also, parallelize the internal slide processing so that the
import completes more quickly. Yay jQuery Deferreds!!!
Backport 1.3.2
Abstract slideset generation to clean up the front-end template.
Clean up and refactor front-end JS
Position and style footer bar
Remove alpha options for social sharing slide (since they no longer matter)
Add styling for new footer bar
Refactor Overlays

Make sure the buttons that trigger overlays actually trigger the
appropriate overlays and populate the correct data.
Make sure other footer buttons close the overlay
Wire in social sharing behavior
Make sure the sharing works with appropriate URLs regardless of embedded or native state.
Update product_key validation logic. props @carldanley
Only show full-screen icon in embedded mode
Make the full screen button work
Add title tags
Make sure overview link button works
Add a close icon when the overlay is active
Clean up some unnecessary styles and scripts
Auto-hide the Footer bar

Make sure the footer disappears as expected (and throttle the callback event) so it doesn't hurt the page.