Updating the Membership.approve method

- Using lessons learned from the Membership.renew method
Updating the Membership.set_member_number method

- Setting the member number on the membership object and returning the member number as well
Updating the membership.renew method

- Not creating duplicates when the membership object is pending

- This method would sometimes create duplicate membership records.  It was difficult to see this extra records because the membership record would immediately get archived

- Sometimes a superusers would receive an email linking to an archived membership because of this renew method