Raise a more descriptive error message by reporting the erroneous box name and available box names.

[BuysDB]

I've added a more descriptive error message by reporting the erroneous box, and which ones are available allowing for faster troubleshooting.

Thanks for this nice library!

[kushalkolar]

I was going to add this feature too until I saw this, would be great if it could be merged in the next pypi release :)