Update __init__.py

[tglarner]

Add dots for import search in the local directory.
This fixes import problems experienced in a jupyter environment for python 3.5

[bfh-reseiwe]

This one should really be merged, in python 3 "import commpy" fails with:

>>> import commpy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.5/dist-packages/commpy/__init__.py", line 17, in <module>
    from filters import *
ImportError: No module named 'filters'

This pull request fixes the problem for me.