Foliantcontrib.swaggerdoc

- Add: strict behavior option and tests

- Fix: a specific version of ruamel.yaml was used

- New utils module.

- Fix: build failed when spec referenced to other files with $ref.

- Fix spec path issue.
- Fix: jinja mode default template wansn't copied.

- Add `spec_path` and `spec_url` parameters.
- All path tag parameters are now loaded relative to current file.
- Better logging and error reporting