LP#1303544 Trim junk from the ISBN in record summary

When asserting that we are publishing an ISBN, move the "(pbk.)"
and similar such matter outside of the schema.org <span property="isbn">
element.

See "The walking dead" in the sample dataset for an example.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Ben Shum <bshum@biblio.org>