Don't display the "Download Diff" link in the diff viewer when viewing an interdiff. It's confusing and leads to a broken URL.
Don't display the "Download Diff" link in the diff viewer when viewing
an interdiff. It's confusing and leads to a broken URL.

Fixes bug #873.




1tush/reviewboard,1tush/reviewboard,bkochendorfer/reviewboard,atagar/ReviewBoard,Khan/reviewboard,chazy/reviewboard,beol/reviewboard,atagar/ReviewBoard,1tush/reviewboard,davidt/reviewboard,KnowNo/reviewboard,KnowNo/reviewboard,KnowNo/reviewboard,reviewboard/reviewboard,beol/reviewboard,brennie/reviewboard,1tush/reviewboard,chazy/reviewboard,atagar/ReviewBoard,chipx86/reviewboard,chipx86/reviewboard,bkochendorfer/reviewboard,asutherland/opc-reviewboard,custode/reviewboard,reviewboard/reviewboard,davidt/reviewboard,asutherland/opc-reviewboard,Khan/reviewboard,custode/reviewboard,chazy/reviewboard,chazy/reviewboard,1tush/reviewboard,davidt/reviewboard,1tush/reviewboard,bkochendorfer/reviewboard,chazy/reviewboard,chazy/reviewboard,beol/reviewboard,chipx86/reviewboard,asutherland/opc-reviewboard,sgallagher/reviewboard,Khan/reviewboard,custode/reviewboard,chazy/reviewboard,davidt/reviewboard,Khan/reviewboard,reviewboard/reviewboard,Khan/reviewboard,chazy/reviewboard,atagar/ReviewBoard,asutherland/opc-reviewboard,Khan/reviewboard,custode/reviewboard,atagar/ReviewBoard,atagar/ReviewBoard,Khan/reviewboard,brennie/reviewboard,bkochendorfer/reviewboard,KnowNo/reviewboard,sgallagher/reviewboard,sgallagher/reviewboard,chipx86/reviewboard,chazy/reviewboard,1tush/reviewboard,brennie/reviewboard,beol/reviewboard,reviewboard/reviewboard,Khan/reviewboard,Khan/reviewboard,1tush/reviewboard,atagar/ReviewBoard,brennie/reviewboard,atagar/ReviewBoard,atagar/ReviewBoard,1tush/reviewboard,sgallagher/reviewboard