Added error control

[Foo-Manroot]

I tried running the tool, but dex2jar failed due to reaching the max heap size.

While that's not directly an error of APKHunt, the tool kept going as if everything was fine; which, obviously, made the rest of the checks fail (because there are no decompiled files to grep...).

That's why I added a bit of error control.

I also took the liberty to run gofmt to automatically format the code according to the official guidelines. Feel free to reject this pull request if you don't want those changes, and I will open a new one without the auto-format.