API should return None from an bad object, not fail for the whole list

[RoyWilliams]

See here
https://community.lsst.org/t/l-sherlock-objects-skips-all-data-if-it-doesnt-find-one/8387/3

[RoyWilliams]

• There should be a limit on the number of objectIds in the list sent to the API for the lightcurves, objects, sherlock_objects, and sherlock_positions methods.
• The limit should be in the settings file
• Error return should be 404 for objectIds that don't exist, and should include a message saying which objectIds have failed to be resolved.