Update port to 8080 to not conflict with Dapr anymore

[simonjj]

Purpose

• port change from 3500 to 8080
• update readme

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[X] Other... Please describe: port change

How to Test

• docker build -t albuncs .
• docker run -it -p 8080:8080 albuncs
• access http://localhost:8080/

What to Check

• check to make sure the app comes up and serves on 8080