Fix tondarray and fromndarray.

Don't use 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.

Now that fromndarray is actually working, these tests are actually
being run. Some of the tests of bitwise operations had to be removed
because they don't work with the default data.
Add vectorize decorator.

Analogous to NumPy's vectorize decorator.
Make _key_and_push check for distarrays.

In Context in client.py
Add local decorator to Context.

stolen from odin.py. However functionality is reduced. It's first
argument must be a distarray and no others can be DA's.
Shouldn't we make numpy available on the engines?
WIP vectorize changes
vectorize and local decorator tests.
WIP fix vectorize decorator in client.py