Update bundle creation.

Deprecating 2.x and 3.x bundles. Adding 5.x bundle.

We will no longer be supporting 2.x and 3.x bundles! If you're still using CircuitPython 2.x or 3.x, please update to the latest! If you are not in a position to do so, please download the final releases of the 2.x and 3.x bundles from 9 September 2019.