Register RA Models from EDS TDS Server

[mwengren]

Register all RA models hosted on the EDS TDS instance in IOOS Catalog.

Note: this necessitates RPS creating some type of attribution allowing a reference back to the source RA TDS or other server hosting the data. This is in order to allow users a way to access the source data if they want.

Related to #40. This should be an easier pathway to increase the model coverage in the Catalog. RAs can still register their own services if they want via Harvest Registry.

[mwengren]

@kbailey-noaa Did we decide on whether/how to include metadata from the EDS THREDDS server for RA model output in IOOS Catalog?

I'm trying to clean up lingering issues for our Jan 29 Catalog 1.6 milestone, and this is one of them. It also might allow us to close out #40 at some point because there isn't any traction moving that along.