Fix package_name value in AddonPackage namedtuple.
Fix package_name value in AddonPackage namedtuple.

When fabsetup is installed as a pip package the parent dir of the module
dir is named 'site-packages'.  Instead of the parent dir of the modules
dir the module dirname will be taken as package name, with each '_'
converted to a '-'.

theno/fabsetup,theno/fabsetup