Update CC license selector to reflect the current version (4.0)

[oceanofsound]

On two separate occasions, users have written to me asking why they can't select the current 4.0 CC license of their choosing within the Hydrus app. I'll admit I'm not a Hydrus user, but I see a couple of issues here:

1. Is it clear in the current UI what version CC license a user is selecting (i.e. is there a distinction between 3.0 and 4.0)?

2. If it's not clear, should a user assume they're selecting the most current CC version? (likely yes)

3. Even if the version number is obscured in the drop down, how can we ensure the most current CC version is assigned to the object at the point of creation?

For more context, see https://github.com/sul-dlss/purl/issues/321#issuecomment-549449076