emaint: Assign all module __init__.py's __doc__ to a variable intsead

Due to distutils-r1 eclass optimization level, __doc__ strings are removed, breaking the
plugin system's use of __doc__ for it's module description(s).
This causes tracebacks when trying to run emaint.

brian@big_daddy $ emaint -h
Traceback (most recent call last):
  File "/usr/lib/python-exec/python2.7/emaint", line 36, in <module>
    emaint_main(sys.argv[1:])
  File "/usr/lib64/python2.7/site-packages/portage/emaint/main.py", line 161, in emaint_main
    parser = ArgumentParser(usage=usage(module_controller))
  File "/usr/lib64/python2.7/site-packages/portage/emaint/main.py", line 78, in usage
    desc = textwrap.wrap(module_controller.get_description(mod), 65)
  File "/usr/lib64/python2.7/textwrap.py", line 354, in wrap
    return w.wrap(text)
  File "/usr/lib64/python2.7/textwrap.py", line 325, in wrap
    text = self._munge_whitespace(text)
  File "/usr/lib64/python2.7/textwrap.py", line 154, in _munge_whitespace
    text = text.expandtabs()
AttributeError: 'NoneType' object has no attribute 'expandtabs'
brian@big_daddy $

Problem found by: Zac Medico <zmedica@gentoo.org>