Bring cloudpickle inside the repository. (#1445)

* Bring cloudpickle version 0.5.2 inside the repo.

* Use internal copy of cloudpickle everywhere.

* Fix linting.

* Import ordering.

* Change __init__.py.

* Set pickler in serialization context.

* Don't check ray location.

python/ray/cloudpickle/__init__.py

@@ -0,0 +1,5 @@
+from __future__ import absolute_import
+
+from ray.cloudpickle.cloudpickle import *
+
+__version__ = '0.5.2'