Remove breadcrumb separator from template.
Remove use of $_FILES superglobal.

In the process, we are also removing a hack to allow multiple file uploads
which no longer works with the new request interface. The breakage occurs
due to the type casting done on the variables. Multi-file uploads will be
handled using Plupload, so this is not an issue.
Remove "Add field" option from screenshot uploader that allows multi-uploads.

This feature will be replaced by a new interface powered by Plupload.