Syntax highlighting

This push does the following:
* Removes the "drop region" from the file upload page
* Separates pages for each submission file
* Adds syntax highlighting, with latency.  Issue: we need to call Prism.highlightAll after content has loaded, but I can't find an Angular event that tells us when rendering is complete.  Right now, I'm doing it with latency so Omar can be unblocked.