Simplify the codebase by removing C and Cython code (for now)

1) Remove all the C-level MPI stuff
2) Remove all the Cython
3) Remove all the stuff needed to build the above (and switch `distutils` for `setuptools`)
4) Update `INSTALL.rst`.
5) Move `docs/examples` -> `examples`.
6) Move `docs/benchmarks` -> `benchmarks`.
7) Move `np_vs_distarray_timing.py` into `benchmarks`.
8) Restore the python `maps.py`
9) Rename `test_odin` so it won't be run by nose (to `exercise_odin.py`).  This allows us to remove `run_tests.sh`.
    We need to fix `odin.local`, but this at least lets us run nosetests for now.
10) Remove `run_tests.sh`
11) Fix a couple of Python 3 incompatibilities introduced by Python `maps.py`.
12) Tweak the Makefile

Resolves #38, #30, #23, #33.

Helps with #6, #32.