Progress: Custom statuses allow blank labels

[neilstudd]

In the "Configure statuses" dialog, it's possible to create statuses with blank descriptions. This seems inconsistent with other features, e.g. you can't create a measurement label with a blank name.

If you create a blank status, and you apply it to a node, the Progress Stats dialog renders blank labels with their numeric identifiers instead.

My feeling is that it shouldn't be possible to create statuses without a description.