Fix upload issue between obj and example objs

[blewert]

If you switch from uploaded object to example object, and the previous example object is the same as the new one, it doesnt update. This is because oldObjSource and oldObjPath still keep their values when set. To recreate:

• Switch to Bunny example
• Upload bomb.obj.
• Switch to Bunny example. It won't update.

Or:

• Switch to Suzanne example
• Upload bomb.obj
• Switch to Bunny example
• Upload bomb.obj. It won't update.

This method of updating is pretty jank to be honest. Needs some way that redux can directly call the methods like updateObjectPath(x) or updateObjectSource(x) without relying on the componentDidUpdate method.