media type

[marqh]

the unidata NetCDF maintainers have recently provisionally registered a new media type with IANA

Unidata/netcdf#42

enabling the use
application/netcdf
within binary array ld libraries for netCDF

issue scope:

• update code base to use application/netcdf in preference to application/x-netcdf

[marqh]

required for v0.4 of netcdf-ld application/netcdf