add suport for python 2.4

new style classes are not supported in 2.4 removed it

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>
add support for python 2.4

python 2.4 does not ship with ctypes so if the user has not installed
that package fingerprint is not able to dinamically trace the process

Properly handle this case giving the user a understandable error

Signed-off-by: Luca Clementi <luca.clementi@gmail.com>