Fix travis configuration for python3

Author: ildus

Makefile

@@ -74,3 +74,5 @@ isolationcheck: | submake-isolation
 		--temp-config=$(top_srcdir)/$(subdir)/conf.add \
 		--outputdir=./isolation_output \
 		$(ISOLATIONCHECKS)
+partitioning_tests:
+	$(MAKE) -C tests/python partitioning_tests

travis/apt.postgresql.org.sh

@@ -126,6 +126,7 @@ EOF
 
 echo "Running apt-get update ..."
 apt-get update
+apt-get install python3
 
 cat <<EOF
 

travis/pg-travis-test.sh

@@ -98,9 +98,7 @@ source /tmp/envs/pg_pathman/bin/activate
 pip install $pip_packages
 
 # run python tests
-cd tests/python
-PG_CONFIG=$config_path python -m unittest partitioning_test || status=$?
-cd ../..
+make USE_PGXS=1 PG_CONFIG=$config_path partitioning_tests || status=$?
 
 set -u