code: function(eventType, commandClass)
  	{
  		if (!eventType) throw new Error('eventType cannot be undefined');
  		if (!commandClass) throw new Error('commandClass for '+eventType+' cannot be undefined');
  		
  		if (this.__commands[eventType] && this.__commands[eventType].indexOf(commandClass) != -1)
  		{
  			return this;
  		}
  		
  		this.__commands[eventType] = this.__commands[eventType] || [];
  		this.__commands[eventType].push(commandClass);
  		
  		return this;
  	}
docs: Map specified Command class the given event
  @param	{string}	eventType - The name of the event
  @param	{class}		commandClass - The command class to instantiate when the event is dispatched