Add framework for executing tests against multiple postgresql versions using docker compose.

tests/integration/main.cpp

@@ -0,0 +1,10 @@
+#include <gtest/gtest.h>
+
+#include "PgTestEnvironment.h"
+
+int main(int argc, char *argv[])
+{
+	::testing::InitGoogleTest(&argc, argv);
+	::testing::AddGlobalTestEnvironment(new pgtest::PgEnv(PGTEST_FIXTURE_DIR));
+	return RUN_ALL_TESTS();
+}