Binary file view double-escapes download link

[Matt Giuca]

In the file view for a binary file, we present a link to the download page, but URLs are double-percent-encoded, so it breaks for any file with special characters. For example, I made a binary file called "A PDF file with spaces in it.pdf" and got a link:
A%2520PDF%2520file%2520with%2520spaces%2520in%2520it.pdf

Expected result:
A%20PDF%20file%20with%20spaces%20in%20it.pdf

Note that the link is generated client-side.

This is high-priority, as it affects submission verification when a student has submitted a binary file.