Run the preparation sequence required to start a salt-api daemon.

        If sub-classed, don't **ever** forget to run:

            super(YourSubClass, self).prepare()

def prepare(self):
        '''
        Run the preparation sequence required to start a salt-api daemon.

        If sub-classed, don't **ever** forget to run:

            super(YourSubClass, self).prepare()
        '''
        super(SaltAPI, self).prepare()

        try:
            if self.config['verify_env']:
                logfile = self.config['log_file']
                if logfile is not None and not logfile.startswith(('tcp://',
                                                                   'udp://',
                                                                   'file://')):
                    # Logfile is not using Syslog, verify
                    with salt.utils.files.set_umask(0o027):
                        verify_files([logfile], self.config['user'])
        except OSError as err:
            log.exception('Failed to prepare salt environment')
            self.shutdown(err.errno)

        self.setup_logfile_logger()
        verify_log(self.config)
        log.info('Setting up the Salt API')
        self.api = salt.client.netapi.NetapiClient(self.config)
        self.daemonize_if_required()
        self.set_pidfile()