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.py b/lava_helper/lava_helper.py
index 783ed04..737626d 100755
--- a/lava_helper/lava_helper.py
+++ b/lava_helper/lava_helper.py
@@ -433,13 +433,13 @@
     over_g.add_argument("-ou", "--override-jenkins-url",
                         dest="jenkins_url",
                         action="store",
-                        help="Override %(jenkins_url)s params in config if "
+                        help="Override %%(jenkins_url)s params in config if "
                              "present. Sets the jenkings address including "
                              "port")
     over_g.add_argument("-oj", "--override-jenkins-job",
                         dest="jenkins_job",
                         action="store",
-                        help="Override %(jenkins_job)s params in config if "
+                        help="Override %%(jenkins_job)s params in config if "
                              "present. Sets the jenkings job name")
     parse_g.add_argument("-tp", "--task-lava-parse",
                          dest="lava_results",