Bug 15006 Correct indentation of EXPORTs in Sip.pm

Bug 15006 Correct indentation of EXPORTs in Sip.pm

Removed tabs and used spaces consistently
Used 'use base' to remove unnecessary BEGIN sub and
explicit setting of ISA at application level

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 4ad4ab6396af26bed9dceb442adf4aad6687f362)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>
(cherry picked from commit ad235daaa74193947a328f96ed35d43aa0ec6663)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>