Actually Implement Configuration Salesforce URL

Looks like an oversight got spotted. On the configuration settings users have an option to change the default Salesforce URL from https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8 to something else. The saved setting was not even being used, the salesforce url is still https://www.salesforce.com/servlet/servlet.WebToLead?encoding=UTF-8

This issue is here to fix this bug.