Move logfiles to resultDir after evaluation finished

Reimplement the behavior that copies log files to the
`resultDir`, which was most likely lost when restructuring
MiniNDN. Parts of the patch are reused from an old
MiniNDN revision.

Change-Id: I3045237950320d1eb7840af9828459e47f6d9884
diff --git a/examples/ip_rounting_experiment.py b/examples/ip_rounting_experiment.py
index a6a82c0..d33e51a 100644
--- a/examples/ip_rounting_experiment.py
+++ b/examples/ip_rounting_experiment.py
@@ -50,4 +50,4 @@
 
     ndn.net.pingAll()
 
-    ndn.net.stop()
+    ndn.stop()