Log Message:
Updated to version 0.9.15.

This release focuses especially fixing the remaining MAC failed errors that
people have been experiencing and the infamous Error in select() error which
should now finally be gone.  Upgrading is strongly recommended.

Changes:

- Fixed KICK command to not send the command reply twice.
- Fixed the QoS unregistering to avoid the errors in select() for invalid
  socket connection.
- Fixed the rekey protocol timeout handling
- Fixed the packet processing to avoid clearing QoS data underneath the QoS.