LP1754455 Add Ability to remove fields or subfields in marc_export

LP1754455 Add Ability to remove fields or subfields in marc_export

This commit adds a --strip option to marc_export that allows fields
and/or subfields to be removed from MARC records on export.

To test: Try all forms of --strip:
    --strip <tag>	e.g. --strip 856
    --strip <tag>/<sub>   e.g.  --strip 856/0
    --strip /<sub>   e.g. --strip /0

Try some regular expressions:
    --strip 8..
    --strip /[ab0]

For all tests, compare the regular output to the stripped otput and
the plain (unstripped) output.

Signed-off-by: Dan Pearl <dpearl@cwmars.org>
Signed-off-by: Jason Boyer <JBoyer@equinoxOLI.org>