acquire() never resolves/rejects if factory always rejects

[Aleksandras-Novikovas]

Example: your network is down and your connection factory always rejects. Trying to acquire never resolved/rejected - pool goes into loop and never stops.
Here code with factory which always fails:

class BadResourceFactory {
    create() {
        return new Promise(function(resolve, reject) {
            var resource = {
                res: "Resource"
            };
            log.info("Created", resource);
//            resolve(resource);
            reject(new Error("Creation error"));
        });
    }
    destroy(resource) {
        return new Promise(function(resolve) {
            log.info("Destroyed", resource);
            resolve();
        });
    }
    validate(resource) {
        return new Promise(function(resolve) {
            log.info("Validated", resource);
            resolve(true);
        });
    }
}

pool.on('factoryCreateError', function(err){
    log.error({err: err}, "Factory create error");
});

var pool = genericPool.createPool(new BadResourceFactory(), {
    min: 1,
    max: 10
});

var res = pool.acquire();

res.then(function(res) {
    log.info({res: res}, "Got resource");
}).catch(function(err) {
    log.info({err: err}, "NO resource");
});

My suggested solution would be:
add option maxTries which would define number of consequent failures before pool stops trying.
Internal counter should be restarted on each acquire() call.

I will clean up my test code and will open pull request.

Regards

EDIT: pull request is added.