fix make distcheck with python tests

- bscs.config needed by the vty tests was not picked up as a dist file, because
  its suffix is not 'cfg'. Rename to *.cfg. Apply this rename in
  vty_test_runner.py and osmo-bsc_nat.cfg.
- Remove restart counters after external tests, otherwise distcheck complains
  about uncleaned files.
- Add contrib/ipa.py to EXTRA_DIST, hence add a Makefile.am to contrib/.
  Otherwise the python tests cannot find that dependency.

Change-Id: I42b55cb1125099afc3a8e3f87c0e398426b2e2a9
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 9cbc1c1..72161ee 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -87,7 +87,7 @@
 if BUILD_SMPP
 	$(PYTHON) $(srcdir)/smpp_test_runner.py -w $(abs_top_builddir) -v
 endif
-	rm -f $(top_builddir)/hlr.sqlite3
+	rm -f $(top_builddir)/hlr.sqlite3 $(top_builddir)/gsn_restart $(top_builddir)/gtphub_restart_count
 else
 python-tests: $(BUILT_SOURCES)
 	echo "Not running python-based tests (determined at configure-time)"
diff --git a/tests/vty_test_runner.py b/tests/vty_test_runner.py
index 92775d5..68a697d 100644
--- a/tests/vty_test_runner.py
+++ b/tests/vty_test_runner.py
@@ -1220,7 +1220,7 @@
 def nat_bsc_reload(x):
     x.vty.command("configure terminal")
     x.vty.command("nat")
-    x.vty.command("bscs-config-file bscs.config")
+    x.vty.command("bscs-config-file bscs.cfg")
     x.vty.command("end")
 
 def nat_msc_ip(x, ip, port):