Bug TDS-526 / Added ECMWF DRS 50002 support

Hi there,

we added support for ECMWF DRS 50002 as discussed in http://www.unidata.ucar.edu/mailing_lists/archives/netcdf-java/2014/msg00048.html

Bug @ https://bugtracking.unidata.ucar.edu/browse/TDS-526

Feedback welcome...

Cheers,
Jochen