Added `mpi4py` and `bokeh` to get the executables working.
Also simplified the `lib.optional` expression as Python 3.2 and 3.4
aren't supported anymore. Rather than referencing unsupported Python 3.x
versions it's far more obvious now to only use `futures` and
`singledispatch` if Python2 is used.
There is a bug when using git repo in that the package does not get a
version (shows up as `0+unknown`). Using pypi fixes this issue allows
allows for auto upgrades.
The github repository was downloaded instead of the pypi repository
for testing (needed `conftest.py`). Major work was done on the
underlying dependencies to make distributed work on python 2.7,
3+. Note that the test **do** take a significant amount of time (10-15
minutes).
- moved to `python-modules`
- compatible with 2.7, 3+
- all tests pass (previously tests were not run)
