Fixing Issue #216 Python bindings

Created by: williamfgc

Copy constructor was implicitly removed for ADIOSPy due to m_ADIOS.

PyBind11 needed the copy constructor.

m_ADIOS is now a shared pointer to avoid copy constructor removal

Separated MPI nonMPI test as ctest failed for MPI

Created by: chuckatkins

Since the adios python object is the only thing that access the adios c++ object, should it be a unique_ptr instead of a shared_ptr?

Created by: williamfgc

@chuckatkins good point....std::unique_ptr has its copy constructor deleted by definition. Clang will do the same thing and delete ADIOSPy copy constructor since m_ADIOS copy constructor doesn't exist for a deep object copy. I use shared_ptr most of the time as we don't know what we end up doing later (putting this inside a thread, using with libraries, etc.) std::unique_ptr has too much "static"-like behavior.