Remove some unused cruft.
One character fix to close issue #258.

Also a small PEP8 change.
Refactor make_grid_shape and optimize_grid_shape to 1 thing.
Remove test for unused function
Add tests for new 1's in grid_shape stuff.

Some PEP8 too.
Remove duplicate test.
Remove incorrect docstring.
Add tests with prime cluster.
Remove unused functions, divisors and outer_zip
Add LocalArray.base, .ctypes
Merge pull request #274 from cowlicks/make-grid-shape-work

Allow and test 1's in `grid_shape`
Refactor key cleanup on client.
Remove `del foo` in favor of `context.cleanup_keys()`
Remove IpclusterTestCase

This was only providing a self.client attribute which was only actually
used in one test class. Its checks and cleanups were unnecessary.
Remove __del__ def from Context
Change cleanup_keys to cleanup.

This reflects the action rather than the implementation since keys are
an implementation detail.
Fix purge_cluster script
Cleanup context in tests. Add Client.close() to Context.cleanup().