rgw_swift: newer versions of boost/utility no longer include in_place

rgw_swift: newer versions of boost/utility no longer include in_place

boost > 1.58 no longer includes in_place in boost/utility, we need to
include in_place_factory explicitly. This causes build failures in
distros that ship with a higher version of boost. Since the only call is for
swift_ver_location, another possibility is to use emplace()
instead (though this requires boost ~ 1.56)

Fixes: http://tracker.ceph.com/issues/16391
Signed-off-by: Abhishek Lekshmanan <abhishek@suse.com>