build: fix system tests, move to Kokoro (#372)

diff --git a/synth.metadata b/synth.metadata
new file mode 100644
index 0000000..ebfeb7f
--- /dev/null
+++ b/synth.metadata
@@ -0,0 +1,12 @@
+{
+  "updateTime": "2019-09-12T22:40:28.148018Z",
+  "sources": [
+    {
+      "template": {
+        "name": "python_library",
+        "origin": "synthtool.gcp",
+        "version": "2019.5.2"
+      }
+    }
+  ]
+}
\ No newline at end of file