[Bf-python] default sys.path to include site-packages

[antont at kyperjokki.fi]

could someone please fix the default sys.path to have the usual places 
like /usr/lib/site-python/ and /usr/lib/python2.4/site-packages/ on a 
debian/ubuntu system.

Stephen already once looked at the place in the bpy sources for this, and 
reminded me about the site module, the docstring of which seems to be:
     Append module search paths for third-party packages to sys.path.

can do myself later but am busy with other things now

~Toni