Can't update the CRM DOM object in WP frontend

WordPress won't allow page content to update the header (https://issues.civicrm.org/jira/browse/CRM-13634) so the pub_key doesn't get saved under CRM.stripe.pub_key.  This adds it via some inline javascript.

Without this, the x-1.8 versions of civicrm_stripe will not work for WordPress.