SumoLogic custom URL

For the Sumologic integration, today we only allow customers to create a "new" integration with a new Sumologic account.  For customers with existing Sumologic accounts, we don't have a way to send data to the existing account.  In addition to new account creation, and the id/key terminology, we should also provide for a customer to give the URL directly (no credentials are required in this use case) which could then be inserted directly into logback.xml.