Add data center contact

[mortenwh]

• Add data center contact when creating MMD from netcdf
• Existing MMD files should be updated accordingly.

The data center contact can be hardcoded based on the naming_authority provided in the nc-files. For no.met, it should be:

<mmd:personnel>
  <mmd:role>Data center contact</mmd:role>
  <mmd:name>Data Management Group</mmd:name>
  <mmd:email>data-management-group@met.no</mmd:email>
  <mmd:organisation>Norwegian Meteorological Institute</mmd:organisation>
</mmd:personnel>