Why are these changes needed?
Add API stability annotations for datasource classes, and add a linter to check all data classes have appropriate annotations.
* Remove all __future__ imports from RLlib.
* Remove (object) again from tf_run_builder.py::TFRunBuilder.
* Fix 2xLINT warnings.
* Fix broken appo_policy import (must be appo_tf_policy)
* Remove future imports from all other ray files (not just RLlib).
* Remove future imports from all other ray files (not just RLlib).
* Remove future import blocks that contain `unicode_literals` as well.
Revert appo_tf_policy.py to appo_policy.py (belongs to another PR).
* Add two empty lines before Schedule class.
* Put back __future__ imports into determine_tests_to_run.py. Fails otherwise on a py2/print related error.
* custom action dist wip
* Test case for custom action dist
* ActionDistribution.get_parameter_shape_for_action_space pattern
* Edit exception message to also suggest using a custom action distribution
* Clean up ModelCatalog.get_action_dist
* Pass model config to ActionDistribution constructors
* Update custom action distribution test case
* Name fix
* Autoformatter
* parameter shape static methods for torch distributions
* Fix docstring
* Generalize fake array for graph initialization
* Fix action dist constructors
* Correct parameter shape static methods for multicategorical and gaussian
* Make suggested changes to custom action dist's
* Correct instances of not passing model config to action dist
* Autoformatter
* fix tuple distribution constructor
* bugfix
