Global scheduler skeleton (#45)

* Initial scheduler commit

* global scheduler

* add global scheduler

* Implement global scheduler skeleton.

* Formatting.

* Allow local scheduler to be started without a connection to redis so that we can test it without a global scheduler.

* Fail if there are no local schedulers when the global scheduler receives a task.

* Initialize uninitialized value and formatting fix.

* Generalize local scheduler table to db client table.

* Remove code duplication in local scheduler and add flag for whether a task came from the global scheduler or not.

* Queue task specs in the local scheduler instead of tasks.

* Simple global scheduler tests, including valgrind.

* Factor out functions for starting processes.

* Fixes.

test/runtest.py

@@ -268,7 +268,7 @@ class APITest(unittest.TestCase):
       return x + 10
     while True:
       val = ray.get(f.remote(0))
-      self.assertTrue((val == 10) or (val == 1))
+      self.assertTrue(val in [1, 10])
       if val == 10:
         break
       else: