Fix tondarray and fromndarray.

Don't use IPython's scatter and gather anymore.

These are pretty slow and should be sped up in the future. This can be
done by speeding up __getitem__ and __setitem__.
Allow distarray ufuncs to take casting kwarg.
Correct tests for distributed ufuncs.

These tests were previously broken.
Some of the tests of bitwise operations had to be removed
because they don't work with the default data.
Add tests for fromndarray and tondarray.
Fix link to readthedocs in the README
Add previously broken tests.
Change assertions to exceptions.
fromndarray bugfix. Add notes about to/fromarray performance.
Move RandomModule class to its own module. random.py
Maintenence on Random class.

* Rename the class RandomModule -> Random
* Add docstrings mostly from NumPy.
* pep8
* fixbugs from old api changes
Add random import to __init__.py
Add tests for random.py

These tests are pretty dumb, they only check that we are getting the
correct shapes returned.
Remove RandomModule from client.py
Add build notes for hdf5 and h5py.
Link to the HDF5 build notes in index.rst.
Generalize `from_distarray` to take a dict as well.

Now, this method will take an object with a `__distarray__` method that returns a dict, or it will just take a bare dict (provided this is a distbuffer dict as defined by the distributed array protocol).
Add tests for the dict form of `from_distarray`.
Rename a test.
Merge pull request #131 from dmcdougall/fix-readme-link

Fix link to readthedocs in the README
Merge branch 'feature/generalize-from_distarray' into feature/add-flat-file-io