Bug 9811: Fixing JSON validation error for non-javascript string literal characters

Bug 9811: Fixing JSON validation error for non-javascript string literal characters

Issue:
When a patron has backslashes in his circulation notes, the JSON transportation
layer cannot send the message because it will fail JSON validation when trying to
validate backslashed non-literal characters (\s \d ...).
This causes the whole search to fail when even one Borrower has a non-literal
backslashed character in his notes.

Solution:
The Borrowers' circulation notes are filtered through a regexp which doubles all
backslashes to prepare them for the JSON validation routine.

Result:
Backslashes pass through unchanged.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>