Add rest-api handler - devide from s3-handler
Refactor multi-upload and others
Commonize onrequest and on response from s3-handler and rest-handler
Rename function names in s3-handler and rest-handler
Commonize request-handler from s3-handler and rest-handler
Commonize request-handler from s3-handler and rest-handler(2)
Fix a get-operation's bug
Add rest-api's tests
Merge branch 'feature/implement-rest-api' into develop