Build Python bindings with distutils for consistent installs

Build Python bindings with distutils for consistent installs

v5: Manually load shared objects used by the Babeltrace Python module

This patch changes the build system used to compile and install the
Python Bindings. Distutils is used to find the right install directory.
When the install directory generated from the install prefix is not in
the Python search path (PYTHONPATH), we print a warning explaining what
can be done to include it.
It uses Distutils which is part of the Python standard library.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>