Update CMS primary data sets

Addressing issues: https://github.com/cernopendata/opendata.cern.ch/issues/89 https://github.com/cernopendata/opendata.cern.ch/issues/333 https://github.com/cernopendata/opendata.cern.ch/issues/154 https://github.com/cernopendata/opendata.cern.ch/pull/91#discussion_r17281750
https://github.com/cernopendata/opendata.cern.ch/issues/223
@tiborsimko: In the DOI SLA we agreed on "the namespace can be specified, for example. for experiments like CMS “cerndata.cms….”. That's why we used this structure.