Cancel/Stop a model download

[tomzx]

Currently (0.6.10) if you start a model download (by mistake) you cannot cancel it.

[cjpais]

@VirenMohindra curious if this may fit in nicely with some of the model page changes? What do you think

[VirenMohindra]

Yep! This should be trivial to implement in my PR. I wonder if its something we need, since the model sizes aren't particularly large and we already have the ability to delete them once downloaded

[cjpais]

I think if it's a trivial thing to implement, let's do it. I kind of agree that it's probably not necessary. But if it's simple and the UI's easy as well as the actual backend logic to do this, I think maybe let's just have a nice handling.

[VirenMohindra]

added here 3665bbd (#478) !