Treat actor creation like a regular task. (#1668)

* Treat actor creation like a regular task.

* Small cleanups.

* Change semantics of actor resource handling.

* Bug fix.

* Minor linting

* Bug fix

* Fix jenkins test.

* Fix actor tests

* Some cleanups

* Bug fix

* Fix bug.

* Remove cached actor tasks when a driver is removed.

* Add more info to taskspec in global state API.

* Fix cyclic import bug in tune.

* Fix

* Fix linting.

* Fix linting.

* Don't schedule any tasks (especially actor creaiton tasks) on local schedulers with 0 CPUs.

* Bug fix.

* Add test for 0 CPU case

* Fix linting

* Address comments.

* Fix typos and add comment.

* Add assertion and fix test.

doc/source/conf.py

@@ -37,7 +37,8 @@ MOCK_MODULES = ["gym",
                 "ray.plasma",
                 "ray.core.generated.TaskInfo",
                 "ray.core.generated.TaskReply",
-                "ray.core.generated.ResultTableReply"]
+                "ray.core.generated.ResultTableReply",
+                "ray.core.generated.TaskExecutionDependencies"]
 for mod_name in MOCK_MODULES:
   sys.modules[mod_name] = mock.Mock()