v3.4 and v4.0

Recently I was asked to compile a list of all CiviCRM releases since 3.1.0, identifying which were security releases so that we could make sure clients' sites were secure. The organization I work for (Freeform Solutions) is focused on doing sites for other non-profit organizations, many of whom are still running older versions of CiviCRM due to budgetary or other constraints, so we wanted to be sure that no one was running a version known to contain security vulnerabilities.