* Reworked the Component structures.
Rewrote parsing, type checking and serialization code.
Improved the graph component structures.
Added most of the needed k8s structures.
Added model validation (input/output existence etc).
Added task cycle detection and topological sorting to GraphSpec.
All container component tests now work.
Added some graph component tests.
* Fixed incompatibilities with python <3.7
* Added __init__.py to make the Travis tests work.
* Adding kubernetes structures to setup.py
* Addressed PR feedback: Renamed _original_names to _serialized_names
* Addressed PR feedback: Reduced indentation.
* Added descriptions for all component structures.
* Fixed a bug in ComponentSpec._post_init()
* Added documentation for ModelBase class and functions.
* Added __eq__/__ne__ and improved __repr__
* Added ModelBase tests
Alexey Volkov