Add vty command to show summary of all or filtered subscribers

Adds the following commands:

show subscribers all - Display summary of all entries in HLR
show subscribers (imsi|msisdn|cs|ps) ... As above but filter on search field/string
show subscribers last seen - Display only subscribers with data in
Last LU update field, and sorts by Last LU.

Change-Id: I7f0573381a6d0d13841ac6d42d50f0e8389decf4
diff --git a/tests/test_nodes.vty b/tests/test_nodes.vty
index cf1707a..5848fe1 100644
--- a/tests/test_nodes.vty
+++ b/tests/test_nodes.vty
@@ -13,6 +13,10 @@
 OsmoHLR> list
 ...
   show gsup-connections
+  show subscribers all
+  show subscribers (imsi|msisdn) FILTER
+  show subscribers (cs|ps) (on|off)
+  show subscribers last-seen
   subscriber (imsi|msisdn|id|imei) IDENT show
   show subscriber (imsi|msisdn|id|imei) IDENT
   show mslookup services