Support workerman v5

Optimizaion

Merge pull request #121 from xuanyanwow/added-batch-group-count

批量获取群组ID内客户端个数

merge 3.x

Update composer.json

Merge pull request #118 from twomiao/master

Update Gateway

Merge pull request #117 from twomiao/master

Router least connections

Merge pull request #116 from twomiao/master

增加轮询负载均衡

Merge pull request #112 from xuanyanwow/batch-uid-online

Adds CMD_BATCH_GET_CLIENT_ID_BY_UID

Update Gateway.php