Fix Throbber

This PR makes our throbber animated, using CSS3 and FontAwesome. We had a throbber of sorts for when ScanJS was running, but I've also added a throbber for when we are uploading files.

Things to note:
* Addition of FoneAwesome library
* the Throbber for file Input doesn't work exactly correctly because of the optimized fashion the JS is running in. Basically, when we grab all the files and reads them, the JS engine goes ahead and executes the other statements it knows it can, which includes hiding our throbber. :) I will file an issue for this, and update the comment here, but I think it will involve pulling file upload into a worker or something like that.