Update package for Noetic

[sfalexrog]

This P/R updates the package to be Noetic-compatible; in particular:

• package.xml now uses version 3, and has conditional dependencies on python-websocket/python3-websocket for tests;
• tests are updated to run on both Python2 and Python3;
• CI is updated to run in Docker;
• miscellaneous code fixes.

This package is required for web_video_server: RobotWebTools/web_video_server#104

[Tobias-Fischer]

Any news on this? Would be great if it could be merged 👍

[flixr]

Would be great indeed!

[JoaoFilipeResende]

This P/R updates the package to be Noetic-compatible; in particular:

* `package.xml` now uses version 3, and has conditional dependencies on `python-websocket`/`python3-websocket` for tests;

* tests are updated to run on both Python2 and Python3;

* CI is updated to run in Docker;

* miscellaneous code fixes.

This package is required for web_video_server: RobotWebTools/web_video_server#104

I've used this package with web_video_server in Noetic and everything is working just fine. Waiting for the merge. Thanks

[JMaravalhasSilva]

Why hasn't this been merged yet? :(

[duwudi]

Please merge 👍

[roehling]

Merged in fkie/async_web_server_cpp