Can I still upload an application that does not support iOS8+?
I currently have an app that we are releasing for iOS7 and 7.1, but it was rejected because it was not compatible for iOS8.
We are currently in the process of building the iOS8 version, but wanted to release something quickly.
No you can't. I'm not sure the exact date that apple made it mandatory to support iOS 8 but I do know it has passed so any new apps/updates submitted to the app store need to support iOS 8.