Cromwell-tools

- Implement `metadata` for both API and the CLI client.

- Add a `--version` argument to the `cromwell-tools` CLI.
- Fix a minor issue with the docstrings of wait function in API.
- Improve the main readme:
- Add a few sub-sections to the development section.
- Fix some outdated docs.
- Start to render Jupyter notebooks in Sphinx-generated docs.
- Add a whole new CLI quickstart to the documentation.
- Fix an issue that blocks workflows to be submitted if the users don't give a workflow option file.
- Add a `silent` flag to the wait command to control the printing.
- Fix an inconsistent parameter for the `submit` CLI command. (`submit --input_files` becomes `submit --input-files`)

- Cromwell-tools complies with the [Black](https://github.com/python/black) code style now.
- Add Flake8 linting hooks.
- **Drop the support for Python2**: Cromwell-tools will only support running in Python3.x environment from v2.0.0
- Switch to a slimmer PR template.
- Add support for JES-backend OAuth-enabled Cromwell: Cromwell-tools will add `jes_gcs_root `, `google_project `, `google_compute_service_account ` and `user_service_account_json` to the workflows options under the hood if you are using the "Service account" auth option to talk to Cromwell.
- Adding getLogger to cromwell_auth to prevent duplicate logging (kgalens)

- Add support for authenticating with service account contents.

- Fix a bug that prevents submitting a zipped file as a dependency of a workflow.

- Improve the help messages of CLI and add shorthands for `submit` command.
- Fix an issue that can stop local file from being normally processed.
- Fix the failing test by cleaning up the Dockerfile that relies on Oracle Java installer and move to use OpenJDK instead.
- Take the retry policy based on tenacity out from the cromwell-tools for clarity.
- Add token checker before making the header to avoid token expiration with OAuth.
- Fix a bug that prevents generating correct pagination parameters for POST `/query` endpoint.
- Update the pull-request-template.