Support Alicloud OSS

[niejn]

Title

Support Alicloud OSS

Motivation

I am currently working for alibaba, and I encounter marvelous smartopen lib when I am coding. However, it doesn't support Alicloud OSS. So I figured I should add oss support myself. Contributing to opensource community is always my dream.

Tests

still working on integration tests.

Work in progress

70% finished, would love to hear your comments.

Checklist

Before you create the PR, please make sure you have:

• [x] Picked a concise, informative and complete title
• [x] Clearly explained the motivation behind the PR
• [ ] Linked to any existing issues that your PR will be solving
• [ ] Included tests for any new functionality
• [ ] Checked that all unit tests pass

[mpenkov]

Hi, had a brief look at the changes, looks like you're on the right track. Let me know when the code is ready for a review. Thanks!

[feisan]

Any updates?