Re-consider CMR response format

[MattF-NSIDC]

trafficstars

Which is best for our use case?

json might be nice, but it has some complicating features. Eg, the list of links often includes hrefs that are not necessary without enough information to determine which are necessary and which are not.

e.g., 

{'href': 'https://doi.org/10.5067/DC0MLBOCL3EL',
'hreflang': 'en-US',
'inherited': True,
'rel': 'http://esipfed.org/ns/fedsearch/1.1/metadata#'},