Merge pull request #3 from sherbang/master

Python 3 updates broke binary file handling
Add missing image for input_image test case
Need list not iterable
unicode function not in Python 3
Use io.open instead which returns unicode strings in the first place
Fix extensions.mako for Python 3 compatibility
-1 no longer allowed for __import__
Remove the level parameter altogether. This doesn't change the behavior for existing 2.x installs since -1 is the default.