several fixes

- wait for start/stop commands to finish running
- better logs

config/test.jsonnet

@@ -5,6 +5,17 @@
     },
   },
 
+  start: [
+    ['err'],
+    ['sleep', '10'],
+  ],
+
+  stop: [
+    ['sleep', '1'],
+    ['false'],
+    ['true'],
+  ],
+
   streams: {
     tailDown1: {
       cmd: ['sh', '-c', "echo 1 2 3 4 5 1 2 3 4 5 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 | tr ' ' '\n' | while read i; do sleep 2; echo found $(($i % 10)); done"],