lava_helper: Adjusted power-off timeout

* Set the power-off timeout to 50 seconds
* Fixed a string formatting bug in argument-parser
  documentation

Change-Id: I18fd8b20edefe76818ae571f686ddb2cfad42871
Signed-off-by: Minos Galanakis <minos.galanakis@linaro.org>
diff --git a/lava_helper/lava_helper_configs.py b/lava_helper/lava_helper_configs.py
index 23816e4..2f896e1 100644
--- a/lava_helper/lava_helper_configs.py
+++ b/lava_helper/lava_helper_configs.py
@@ -52,7 +52,7 @@
     "job_timeout": 120,
     "action_timeout": 90,
     "monitor_timeout": 90,
-    "poweroff_timeout": 10,
+    "poweroff_timeout": 50,
     "recovery_store_url": "%(jenkins_url)s/"
                           "job/%(jenkins_job)s",
     "artifact_store_url": "%(jenkins_url)s/"