Update setup.py to embed the demo data mat files in pyfaust wheel packages.

- Adding pyfaust.demo.get_data_dirpath() to return the data directory dynamically from package resource manager (setuptools) and if it fails (that is, most likely pyfaust was installed from system pkgs (macos pkgbuild, linux rpm, deb...) it'll give the matlab data directory path (because in this case we know the matlab wrapper was installed along the python wrapper).
- I didn't test if egg packages properly received the data mat files (only wheel tested but I think it's ok and anyway we prefer wheel packages).

Other minor changes:
- Adding matplotlib as pyfaust dependency in setup.py (for pyfaust.demo).
- Fixing in pyfaust.demo.bsl.run() the creation of demo results output dir.
- Updating pyfaust.FaustFactory.fact_hierarchical() code doc examples to make use of pyfaust.demo.get_data_dirpath().

Related issue: #73