Recruit n participants.

def recruit_participants(self, n=1):
        """Recruit n participants."""
        auto_recruit = os.environ['auto_recruit'] == 'true'

        if auto_recruit:

            print "Starting Wallace's recruit_participants."

            hit_id = str(
                Participant.query.
                with_entities(Participant.hitid).first().hitid)

            print "hit_id is {}.".format(hit_id)

            is_sandbox = self.config.getboolean(
                'Shell Parameters', 'launch_in_sandbox_mode')

            if is_sandbox:
                host = 'mechanicalturk.sandbox.amazonaws.com'
            else:
                host = 'mechanicalturk.amazonaws.com'

            mturkparams = dict(
                aws_access_key_id=self.aws_access_key_id,
                aws_secret_access_key=self.aws_secret_access_key,
                host=host)

            self.mtc = MTurkConnection(**mturkparams)

            self.mtc.extend_hit(
                hit_id,
                assignments_increment=int(n or 0))

            expiration_increment = self.config.get('HIT Configuration',
                                                   'duration')

            self.mtc.extend_hit(
                hit_id,
                expiration_increment=int(
                    float(expiration_increment or 0) * 3600))
        else:
            print(">>>> auto_recruit set to {}: recruitment suppressed"
                  .format(auto_recruit))