Improvements for self-service cancellation of recurring contributions and membership auto-renewal

Currently we provide end-users with a URL to cancel their auto-renew membership at the bottom of the Memberships - Receipt (on-line) message template. However we do NOT provide the same option when recurring contribution starts. We also do NOT log an activity record when a user cancels the auto-renewal for their membership.

• Implement $cancelSubscriptionUrl for recurring contribution and auto-renew membership 'start' notification msg template (Contributions - Recurring Start and End Notification). As done in existing "Memberships - Receipt (on-line), this variable should direct user to contribute/unsubscribe for processors which support API cancellation. Otherwise (I think) it points them to processor website (or we tell them to "login to their account").

• Verify whether $cancelSubscriptionUrl in 'Contributions - Receipt (on-line)' message template also does the right thing (i.e. directs to contribute/unsubscribe. (EFF had said that recurring contributors were not given a cancellation option - but I do so that section present in the 4.2 msg template so not sure what's up).

• Create an activity record for cancellation of recur or auto-renew. Activity source is contact who requested the cancellation (for front-end case, this should be the contributor).

• Contact dashboard should also include "Cancel" link for recurring contributions and auto-renew memberships (built using same logic as cancelSubscriptionUrl in receipts - except that checksum is not needed since user is already logged in). (NOTE: some of this may already be implemented as I saw a reference to that variable in CRM/Contribute/Page/UserDashboard.php)