Ingest auxiliary data from MERIS files

MERIS files include wind, ozone, rel humidity,
and pressure fields which are useful for things
like Rayleigh scattering tool.

Read these fields from the file, and add to
database. We treat them in a similar way to the
angles, with a mean value stored in the database
and the pixel data stored in geo tiffs. Make a
separate geotiff for each parameter, since there's
no logical order to put them in, and we might not
have every one in the future (and there's no way
to name bands in the geotiff).

nb For other sensors where these fields are missing,
the database entries will be null.