add: dynamic waiting with wait-for-it

tests/run_tests.sh

@@ -53,9 +53,13 @@ core_id=$!
 
 
 # wait for start
-sleep 5;
-curl -s -o /dev/null --retry 5 --retry-all-errors --retry-connrefused http://localhost:5000/api/v1/tags
-
+if [ -x "$(command -v wait-for-it)" ]
+then
+    wait-for-it localhost:5000 -t 15
+else
+    echo "waiting 5 seconds for server"
+    sleep 5;
+fi
 
 export PYTHONPATH=$PYTHONPATH:$source_dir/tavern_utils
 tavern-ci --disable-warnings $source_dir/tavern_tests