Fix bug 772. vim_thread tasks key params

Change-Id: I533859eb38a02ff3c084b6d53a735660f4ec46b1
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>
diff --git a/osm_ro/vim_thread.py b/osm_ro/vim_thread.py
index 7b197da..ffe721c 100644
--- a/osm_ro/vim_thread.py
+++ b/osm_ro/vim_thread.py
@@ -258,6 +258,7 @@
                     # task of creation must be the first in the list of related_task
                     assert(related_tasks[0]["action"] in ("CREATE", "FIND"))
 
+                    task["params"] = None
                     if task["extra"]:
                         extra = yaml.load(task["extra"])
                     else: