fix cabal file.
Add closeZeroLinger method to utils.

closeZeroLinger allowes to close socket immideately, no
message will be kept in memory for the future delivery.
Use zero Linger on socket close.
Use closeZeroLinger and remove explicit disconnects.

* closeZeroLinger will guarantee that sockets will be closed
immidiately and no messages will be kept in memory;
* explicit 'disconnect' require additional work.
Add proper exception masking.