added: support server-timeout

+ added: support server-timeout ( server::set_server_timeout() ).
  server-timeout is implemented with mp::wavy's timer. One timer
  is associated per one server-socket.

  WARNING: by restriction of mp::wavy's timer implementation,
  server-timeout feature requires #server-threads > 1 and
  Linux kernel > 2.6.25 .
fix: server-timeout spec changed 'int' into 'double'
added: request cancellation feature

+ future.cancel() added. when a request is cancelled,
  future.get() raise request_cancelled exception.
Merge remote-tracking branch 'origin/devel-juba' into devel-juba
fixed: tcp_builder::reconnect_limit()
fixed: close TCP session if EOF reached

+ fixed: close TCP session if EOF reached
+ added: new msgpack::rpc exceptions are introduced:
    connection_closed_error and system_error
+ modified: connection_closed_error exception is raised
  when client read EOF
+ modified: system_error exception is raised when client's
  read() system-call result in error
+ modified: when server read EOF or read() system-call
  result in error, server close (client) TCP session
fixed: exception string format for simple string
Merge remote-tracking branch 'origin/devel-juba' into devel-juba
changed: rename msgpack-rpc -> jubatus_msgpack-rpc

+ changed: rename libmsgpack-rpc -> libjubatus_msgpack-rpc
+ changed: rename include dir msgpack-rpc -> jubatus/msgpack-rpc
fixed: add null-impl guard for future::cancel
fixed: static_cast<> corrupts const qualifier
fix copyright
eliminate zlib dependency

msgpack-rpc doesn't use zlib(deflate)
so remove description from configure.in
fixed NOTICE, AUTHORS and version

+ libjubatus_msgpack-rpc.so version changed to 0.4.0
update README
Merge branch 'release/0.4.0'