Small tweak to `INSTALL.rst`.

This package also depends on `six`.
Improve basic checks of distarray export.
Add a failing import/export round-trip test.

Also play with names and fix a couple of missed renames in `denselocalarray.py`.
Test keys and values separately.
Test if `__distarray__()['buffer']` returns a buffer.
Modify round-trip test to use new function name.

We've temporarily settled on `fromdap()` for importing from `__distarray__` interfaces.
Export a `dimdict` for every dimension.
Finish implementing distarray export for the DAP*

*: Distributed Array Protocol.
Fix bug in export.
Test exported types in depth.

May be too strict, but the protocol is still evolving (so we'll see).
Fix comment.
Fix bug in test under Python 2.7.
PEP8 tweaks.
Always use `memoryview` instead of `buffer`.
Add extensive tests to DAP roundtrip test.
Rename `dimdata` function to `_dimdata`...

and add a docstring.
Remove trailing whitespace.
Add a `fromdap` function for importing from DAP [1]_

.. [1] Distributed Array Protocol

All the tests pass except for the last one (which tries to assert that the new `LocalArray`'s data attribute is the same object as the original `LocalArray`'s).  So I assume an unintended copy is happening somewhere.
Split out the failing (identity) assertion...

into its own test.
`assert_almost_equal` -> `assert_array_equal`

Since I'm comparing the same buffer to itself (hopefully), I should be able to use exact equality here.