pollEmails -- String of comma-separated email addresses to send polls to.
This function searches the roster for anyone requesting polls. It makes a status check on each member as well, making sure they are not "Reserve." A member must have "Receive Poll Notifications" set and be any status but "Reserve" to be included in the returned recipient list.
This function returns an emtpy string on failure.
pollEmails () /* Returns the string described above. */