Implement get_fapl_mpio that returns the MPI communicator and info objects.

This implementation is based on the suggestion by Matthew Emmett
https://groups.google.com/d/topic/mpi4py/fxJFF7Hmx1Y/discussion

Follows gh-391
Change '*' import to specific names.
Unify unit tests
Fix Dimension Scales error reporting issue
Fix failing unit tests obscured by H5DS error issue
Merge pull request #392 from andrewcollette/issue_389

Fix H5DS eror-reporting problem (Issue 389)
Implement custom path checker
Fix containership corner cases, improve tests
Make new containership test depend on HDF5 1.8.5+
Fix slash-handling glitch for containership tests
Merge pull request #394 from andrewcollette/issue_388

Implement custom containership test
Free MPI_Info and MPI_Comm Cython objects.
Merge pull request #395 from pdebuyl/get_fapl_mpio

implementation of get_fapl_mpio
Allow Unicode field names for slicing on Py2
Merge pull request #396 from andrewcollette/issue_374

Allow Unicode field names for slicing on Py2
Merge master into identifiers branch