Only install ray python packages. (#330)

* Only install ray python packages.

* Add some __init__.py files.

* Install Ray before building documentation.

* Fix install-ray.sh.

* Fix.

src/local_scheduler/test/local_scheduler_tests.cc

@@ -74,7 +74,7 @@ LocalSchedulerMock *LocalSchedulerMock_init(int num_workers,
   UT_string *worker_command;
   utstring_new(worker_command);
   utstring_printf(worker_command,
-                  "python ../../python/ray/workers/default_worker.py "
+                  "python ../../../python/ray/workers/default_worker.py "
                   "--node-ip-address=%s --object-store-name=%s "
                   "--object-store-manager-name=%s --local-scheduler-name=%s "
                   "--redis-address=%s:%d",

src/numbuf/python/test/runtest.py

@@ -3,7 +3,7 @@ from __future__ import division
 from __future__ import print_function
 
 import unittest
-import numbuf
+import ray.numbuf as numbuf
 import numpy as np
 from numpy.testing import assert_equal
 import os