setup.py should check for module.version as a function

[flip]

During a dependency check, setup.py examines various attributes of the modules it imports to try to divine the version number. Some examples:
module.version
module.version
module.VERSION

This currently works for all of the modules on which we're dependent, but it's been pointed out to me that some modules have a version function instead of an attribute. setup.py would be more robust if it took this into account.