almath.py: fix loading libalmath.so
almath.py: fix loading libalmath.so

With new Python SDK layout, almath.py is in lib/python2.7/site-packages,
and libalmath.so in lib/

Change-Id: Ic7ec85f54270eddf022ff99b9ed0cbfbf304ab6d

sbarthelemy/libalmath,sbarthelemy/libalmath,aldebaran/libalmath,aldebaran/libalmath