Bug#733489: python-apt: Improve 'Dependency' and 'BaseDependency' to get target package versions that satisfy dependencies

[Michael Schaller <michael@5challer.de>]

Hi Michael,

From my experience PEP8 and pyflakes are great tools with nearly no 
false positives - especially compared to pylint - and by now they are 
available for Python 2 and 3.
I personally like to add a lint command to setup.py to my projects. 
Maybe this would be beneficial for python-apt too. Please let me know if 
you would like to see a patch for that.

Best,

Michael