Agile Sprint Health Gadget: allow to show health measured in "issue count"

The gadget for the sprint health currently measures the sprint progress in story points. I would like to have a configuration option to be able to measure the progress in issue count as well.

Especially at the end of a sprint, we want to know how many stories are still open, especially to be reviewed. Reviewing an implementation of a story is less related to the story points than the actual implementation, as for instance design decisions do not need to be reconsidered. The effort for reviewing is more related to the pure number of issues to be reviewed.