Start a Bokeh Server Tornado Application on a given Tornado IOLoop.

def initialize(self, io_loop):
        ''' Start a Bokeh Server Tornado Application on a given Tornado IOLoop.

        '''
        self._loop = io_loop

        for app_context in self._applications.values():
            app_context._loop = self._loop

        self._clients = set()

        self._stats_job = PeriodicCallback(self._log_stats,
                                           self._stats_log_frequency_milliseconds)

        if self._mem_log_frequency_milliseconds > 0:
            self._mem_job = PeriodicCallback(self._log_mem,
                                             self._mem_log_frequency_milliseconds)
        else:
            self._mem_job = None


        self._cleanup_job = PeriodicCallback(self._cleanup_sessions,
                                             self._check_unused_sessions_milliseconds)

        if self._keep_alive_milliseconds > 0:
            self._ping_job = PeriodicCallback(self._keep_alive, self._keep_alive_milliseconds)
        else:
            self._ping_job = None