Add more explicit console logging + minor fixes

* The checks with keywords such as "Should Not Be Empty", "Should
  Be Equal As"... should have a more explicit message on fail, so that
  the console output shows a clearer failing reason.
* Other minor fixes included in the commit are:
	* The Sadis file comparison to None string.
	* The KUBECTL_CONFIG variable not properly set, altough
	  apparently unused.

Change-Id: I9305ba791dd43c9088a7bcbcc9af568ae127f60f
diff --git a/tests/dmi-interface/dmi-hw-management.robot b/tests/dmi-interface/dmi-hw-management.robot
index a345426..7c3fd2f 100755
--- a/tests/dmi-interface/dmi-hw-management.robot
+++ b/tests/dmi-interface/dmi-hw-management.robot
@@ -179,7 +179,7 @@
         Log  ${element}
         ${component_uuid}=  utility.get_uuid_from_Inventory_Element  ${element}  ${component_name}
     END
-    Should Not Be Equal  ${None}  ${component_uuid}
+    Should Not Be Equal  ${None}  ${component_uuid}     Could not find UUID for ${component_name}
     [Return]    ${component_uuid}
 
 Loggable Entities