Log Message:
Update ruby-eventmachine to 1.0.4.

## 1.0.4 (December 19, 2014)
* add starttls_options to smtp server [#552]
* fix closesocket on windows [#497]
* fix build on ruby 2.2 [#503]
* fix build error on ruby 1.9 [#508]
* fix timer leak during dns resolution [#489]
* add concurrency validation to EM::Iterator [#468]
* add get_file_descriptor to get fd for a signature [#467]
* add EM.attach_server and EM.attach_socket_server [#465, #466]
* calling pause from receive_data takes effect immediately [#464]
* reactor_running? returns false after fork [#455]
* fix infinite loop on double close [edc4d0e6, #441, #445]
* fix compilation issue on llvm [#433]
* fix socket error codes on win32 [ff811a81]
* fix EM.stop latency when timers exist [8b613d05, #426]
* fix infinite loop when system time changes [1427a2c80, #428]
* fix crash when callin attach/detach in the same tick [#427]
* fix compilation issue on solaris [#416]