Single Tag Rank Method

Process:
   1. Any records that is going to be added is found.
   2. If existing, and if a update is going to be done, existing data is
      loaded from database.
   3. The configuration file is loaded.
   4. Loading knowledgebase file.
   5. Getting records from the database containing the MARC21 tag from the
      configfile, and which are among the ones to be updated.
   6. The function will then go through all records, and if we have the
      value for the record as a key in the kb file, the value from the kb
      file will be associated to this record id. If the record id already has
      a value, this will be replaced if the newest is higher than the old one,
      and if there is no match in kb_data it will get the value -1.
   7. The database is updated.