- change abstractions/postfix-common to allow /etc/postfix/*.db k
- add several permissions to postfix/error, postfix/lmtp and postfix/pipe
- remove superfluous abstractions/kerberosclient from all postfix
  profiles - it's included via abstractions/nameservice


Acked-by: Seth Arnold <seth.arnold@canonical.com> for 2.9, 2.10, 2.11 and trunk