Bug 22943: Renames the in_ipset function to in_iprange in C4::Auth

Bug 22943: Renames the in_ipset function to in_iprange in C4::Auth

Bug 14407 introduced a new system preference to allow limiting the
online self checkout system to an IP or IP Range. The function that
handles this is called in_ipset, which is the name of a linux tool. To
stop confusion, this patch renames the function to 'in_iprange', and the
variable 'ipset' within it to 'iprange'.

To test, follow the test plans outlined in Bug 14407 and confirm that
everything works as expected.

Sponsored-by: Catalyst IT
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>