I downloaded Xcode 7.1 from the App Store today after working from 7.1 beta downloads from developer.apple.com and have a new iOS app build to upload. So I did:
Having the same problems as all of you, just thought I'd share that I found a way to Validate successfully, you have to disable the "Include bitcode" checkbox before moving forward. As for the actual upload to App Store, no work around for that one other than use the Application Loader...
Also I've been seeing this too since XCode 6.4, but it seems once the current version has a couple of months after it's originally released it starts working again... fingers crossed that it starts working again soon, because uploading straight from Organizer is so much better. (I saw the Beta Version post, when I say after a couple of months for current version I'm not talking about Beta versions, just in case ;) )