Sanic-cors

Ported Sanic-CORS to use Sanic-Plugins-Framework!

This is a big change. Some major architectural changes needed to occur.

All tests pass, so hopefully there's no fallout in any user facing way.

No longer tracking SANIC version numbers, we are doing our own versioning now.

- This fixes compatibility with ASGI mode, as well as alternate server runners like gunicorn server runner.

Bump sanic-plugins-framework to latest
Use CIMultiDict from Sanic by default, rather than CIDict
Fix a test which broke after the CIDict change

- There were some recent important bugs fixed in SPF, so we want to specify a new min SPF version.

- This release includes similar pickling fixes in order to solve Windows multiprocessing issues in Sanic-Plugins-Framework

Bug fixes, see git commits