OPAC Browse: Fix browse interface's use of hits-per-page user setting

OPAC Browse: Fix browse interface's use of hits-per-page user setting

The code that consults the user setting 'opac.hits_per_page' to set a
default number of results to show in the browse interface was faulty.

It failed to account for the opac.hits_per_page setting being configured
for storage in a JSON-encoded string. My own earlier testing missed
this because I had set opac.hits_per_page with a plain number in the
database.

Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>