LP#1727345 - fix bibsource when importing or overlaying

LP#1727345 - fix bibsource when importing or overlaying

This addresses several issues that were causing the
bib source to either not display correctly on the record page
or not save correctly when editing z3950 imports/overlays
Refactors passing around of bib source into eg-marc-edit and it's
child directive egMarcEditBibsource.

Two paths to test:
Path A)
    1. Import a new bib record from z3950, but via "Edit then Import"
    2. Bring up marc editor and choose save w/ bib source.
    3. Verify chosen bib source saved correctly on record page.
Path B)
    1. Mark a record as target for Overlay, go to z3950 import.
    2. Make a search, select item for Overlay.
    3. Choose Edit z3950 record to bring up marceditor, save with a bib source.
    4. Verify chosen bib source saved correctly on record page.

Signed-off by: Cesar Velez <cesar.velez@equinoxinitiative.org>
Signed-off-by: Mike Rylander <mrylander@gmail.com>