Sentinel test: added TODO items in 02 unit.

tests/sentinel-tests/02-slaves-reconf.tcl

 # Check that slaves are reconfigured at a latter time if they are partitioned.
+#
+# Here we should test:
+# 1) That slaves point to the new master after failover.
+# 2) That partitioned slaves point to new master when they are partitioned
+#    away during failover and return at a latter time.