Context takes a client argument, no longer takes view.

Context initializes its view attribute with all engines from the client
passed in.  Will initialize with Client() if no client argument
provided.

User can (still) select a subset of client's engines with `targets`
argument.
Removes direct_view instances from testsuite.
Clean up test_client.py's docstring.
Merge branch 'master' into bugfix/context-takes-client

Conflicts:
	distarray/tests/test_client.py
	distarray/tests/test_distributed_io.py
Merge branch 'master' into bugfix/context-takes-client

Conflicts:
	distarray/tests/test_client.py
	distarray/tests/test_distributed_io.py
Changes to reduce functions to support dtype kwargs.
Add tests for reduce functions kwargs.

Also speeds up some slow tests.
PEP8 imports in client.py
Raise NotImplementedError for out and axis kwargs.
Merge pull request #212 from enthought/bugfix/context-takes-client

Context takes a client argument, no longer takes view
Merge branch 'master' into feature/parallel-hdf5-loading
Merge pull request #202 from cowlicks/reduce-dtype

Add support for dtype kwarg in reduce functions.
Merge master and fix.
Merge branch 'master' into feature/parallel-hdf5-loading
Merge branch 'feature/parallel-hdf5-loading' into feature/parallel-npy-loading
Fix errors caused by merge.