Don't pollute the global scope and use Drupal's APIs to add settings/behaviours

when I wanted to look into a different issue I'm having with this module I noticed that it pollutes the global namespace like crazy, even temporary variables that aren't even used outside of the function where they're defined

attached patch is a step in the direction of keeping everything nice and snug within Drupal.behaviors, Drupal.settings.webform_conditional and Drupal.webform_conditional