Airflow-livy-operators

* Bump apache-airflow from 1.10.9 to 1.10.11
* Bump other python libraries' versions
* Make README and code examples a bit more user-friendly.

* Rename from airflow-livy-plugins to airflow-livy-operators.
* Major refactoring, no need to link operators into plugins folder anymore.

Move package: airflow_home to airflow_livy,
improve development and sampling workflow

Supported modes:

Livy Sessions,
Livy Batches with optional additional status validation via Spark/YARN REST API


Full test coverage, CI/CD.