Remove serial ingest references and services

Remove serial ingest references and services

The references and services for serial (MFHD) support are not
necessary in 1.6, as we are working directly with the MFHD as
maintained in serial.record_entry.marc; the services and
references being removed never could have been used in the
1.6.0.0 release and should have been removed prior to the 1.6.0.0
release when I removed the corresponding database structures.

Also updating the README to reflect the proper loading method for
serial records, dropping direct_ingest.pl invocation and noting the
limitation on the org_unit identification.

git-svn-id: svn://svn.open-ils.org/ILS/trunk@15292 dcc99617-32d9-48b4-a31d-7c20da2025e4