Allow choice between GitHub releases

This PR allows users to choose which asset to download in the event that there are multiple compiled assets available (as seen [here](https://github.com/rbray89/ActiveTextureManagement/releases)) asking them which to use when adding/updating instead of simply using the first.
* Already replacing the iterators.
* Sets don't have a "first" method. It kind of sucks, there's no reason they shouldn't.
* I believe you can, but it's a habit. I still usually develop for Java 6 and up, so I like to make things compatible.
* Why the braces? It shouldn't affect the code at all.