cos-nodejs-sdk-slim v2.2.6

cos-nodejs-sdk-slim

modified from: tencentyun/cos-nodejs-sdk-v5

change:

• use sdk/slimRequest.js instead of huge request package
• trim method from sdk/base.js
• delete sdk/advance.js

remaining base method:

• getService
• getBucket
• headBucket
• getObject
• putObject
• putObjectCopy