CMS: addition of 8567 for PAT tuple files

* Adds 8567 field with information about where the ROOT files are, so
  that these can be later served via the portal as "linked" files.
  (addresses #377)

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
records: MARC tag 8567 in data model

* Adds new field `electronic_location` (MARC tag 8567) to the data
  model.  Useful for storing location of files that are living in
  trusted third party systems, not managed locally.  (The former case
  is coded via 8567, the latter case via FFT.)
  (addresses #377)

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>