fix use of noscripting option

With the old code the "properties.mongodb_node.noscripting" flag would be ignored when set to false.
Kind of tricky, but:
  <%= properties.mongodb_node.noscripting || "true" %>
basically says:
   if properties.mongodb_node.noscripting is set to "true" then use it ELSE use "true"
which means its always going to be "true".  When what it really was trying to say is:
   if properties.mongodb_node.noscripting is set at all then use it ELSE use "true"
This patch does it correctly.
in your yml then  "properties.mongodb_noscripting" isn't "true".