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/autoscaler/aws/development-example.yaml

@@ -88,7 +88,7 @@ setup_commands:
     - echo 'export PATH="$HOME/anaconda3/bin:$PATH"' >> ~/.bashrc
     # Build Ray.
     - git clone https://github.com/ray-project/ray || true
-    - pip install -U cloudpickle boto3==1.4.8
+    - pip install boto3==1.4.8
     - cd ray/python; python setup.py develop
 
 # Custom commands that will be run on the head node after common setup.