BibDocFile: fix for bibdoc unattached to record
BibDocFile: fix for bibdoc unattached to record

* Fixes the constructor of the BibDoc class to correctly set the bibrec_types
  class atribute when the bibdoc is not attached to any record.
  (closes #1551)

Reviewed-by: Tibor Simko <c7116e45300b163846dc01f3ed02116e3f8ef7a5@cern.ch>

inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio