WIP julia_distarray.py
Move everything client.py into distarray.* namespace.

This is mainly to make Context easier to access.
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.
WIP clean up julia_distarray.py