Version 0.0.66

* Fixed websocket plugin to display warning when "websocket" module not
installed instead of process crash
* Improved exceptions handling in Impress core, exceptions will be
logged to file, workers will restart, master will exit on exception
* Refactored plugins optional loader for all plugins
* Fixed impress.log.js, prevent exception in case when other application
deletes g
* Fixed parameters in 'exit' event when spawn worker processes