Properly fixed the site-packages symlink advice.  (The problem on some OSes such as Debian Etch or SLC4 x86_64 was caused by existence of more than one 'site-packages' directory in sys.path, with testimport using the first one and intbitset using the second one during 'make install'.  Now testing and advising user to create symlinks for all site-packages directories.)
Properly fixed the site-packages symlink advice.  (The problem on some
OSes such as Debian Etch or SLC4 x86_64 was caused by existence of
more than one 'site-packages' directory in sys.path, with testimport
using the first one and intbitset using the second one during 'make
install'.  Now testing and advising user to create symlinks for all
site-packages directories.)

inveniosoftware/invenio,inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio