SimpleActionState will hang forever if action node dies

[jorgenfb]

On initialization the SimpleActionState will spin up a thread to wait for the action server to become active. This is the only time the state is waiting and checking for the action server to become available. If this initial check succeeds and the action node dies at a later time, then when the SimpleActionState is executed it will no longer check if the server is active, just send the goal and hang there forever.