[B] DIS-376 default FAIRscores to something more consistent

[leojpod]

I've asked the guy who's made the FAIRshake score stuff about a better way to do that but in short ...

- if there is no URL feed to the API the API still returns a score. - until we get a better way to do this, I've defaulted empty URL to no-doi-given and since an URL/DOI that is not graded returns an empty score it works so long as no one "grade" the identifier: no-doi-given...

If there is no DOI, we render an empty FAIRscore directly.

To test it:

• login/create an account,
• register a data set,
• check that the FAIRscore is an empty one.

[leojpod]

if it doesn't work it's @RyanGee 's fault