src/ab/controllers/__init__.py

from os.path import dirname, basename, isfile, join
import glob

modules = glob.glob(join(dirname(__file__), "*.py"))
__all__ = [basename(f)[:-3] for f in modules if isfile(f) and not f.endswith('__init__.py')]

for module in __all__:
    __import__('ab.controllers.{module}'.format(module=module))