Bug 9043: The comma (,) should be kept to separate multi-valuated prefs

Bug 9043: The comma (,) should be kept to separate multi-valuated prefs

The prefs language and opaclanguages used the comma to separate the
different values.

The new prefs OpacAdvSearchMoreOptions and OpacAdvSearchOptions should
do the same.

To reproduce the issue: update the language pref (or opaclanguages) and
refresh the page.
=> The pref values are not checked anymore and the language selection
(bottom of the page) does not appear.

Test plan:
1/ Verify that the behavior described above is fixed.
2/ Verify that the original test plan of bug 9043 still passes.

Note: The 2 OpacAdvSearchMoreOptions and OpacAdvSearchOptions pref
values are overwritten but the feature have just been pushed recently.
It should not affect a production environment.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
I was able to reproduce the issue and verify that this patch corrected
the problem. Langage selection and OpacAdvSearchOptions worked
correctly.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>