Upload location is not validated when config is saved

@amoebanath I have hereby attached the patch for validation of upload location, if it is empty. I could not understand the concept of individual value since, it is a temporary location. Kindly explain an invalid state so that I can create a MR fixing that as well.

I've opened an issue fork that covers the scenarios I thought should reasonably be covered

I think this is important to get in as there have been several issues I've seen that revolve around putting the wrong (or no) upload location so assigning to me to review and test.