MD5 Reborned Hasher is incompatible with Firefox 20

Originally created by @sajolida on #6245 (Redmine)

MD5 Reborned Hasher is incompatible with the new layout of the Downloads window in Firefox 20 and later.

We need to wait for that bug to be fixed before updating our documentation on ISO verification with Firefox.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information