[wip] travis: properly kill postgres process

[skip appveyor]

Author: ales-erjavec

.travis/install_postgres.sh

@@ -36,6 +36,8 @@ fi
 # Create a new database dir, create database test and register extensions
 $POSTGRES/bin/initdb -D $TRAVIS_BUILD_DIR/db
 $POSTGRES/bin/postgres -D $TRAVIS_BUILD_DIR/db -p 12345 &
+POSTGRES_PID=$!
+
 sleep 1
 $POSTGRES/bin/createdb -p 12345 test
 $POSTGRES/bin/psql test -c 'CREATE EXTENSION quantile;' -p 12345

.travis/stage_after_success.sh

@@ -1,4 +1,8 @@
 
+if [ "$POSTGRES_PID" ]; then
+    kill $POSTGRES_PID && wait $POSTGRES_PID
+fi
+
 [ "$RUN_PYLINT" ] && return 0  # Nothing to do
 
 if [ "$BUILD_DOCS" ] &&