* Change subject from "Failed Processing Activity" to
  "Activity failed: <path>/<method>"
* The subject starts with "Pending activity already failed <failures> times:"
  if CMFActivity is going to reexecute indefinitely.
* Drop the first line of the body. It was repeating the the subject.
* Add number of failures.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32880 20353a03-c40f-0410-a6d1-a30d3c3de9de