SGSN: introduce NS tests

Similiar to the PCU_Tests_NS introduce SGSN_Tests_NS.

Change-Id: Ib2bffbb110961474928f35d212cb492d4b6fdee0
diff --git a/sgsn/SGSN_Tests.cfg b/sgsn/SGSN_Tests.cfg
index d6182eb..d5c3a4c 100644
--- a/sgsn/SGSN_Tests.cfg
+++ b/sgsn/SGSN_Tests.cfg
@@ -42,3 +42,4 @@
 [EXECUTE]
 SGSN_Tests.control
 SGSN_Tests_Iu.control
+SGSN_Tests_NS.control