Analyze Scripts not in a Package

Currently we only analyze scripts that are part of a setup.py described package. This PR adds extra code to the scanner that will bundle up all unaccounted scripts, and put them in a source unit of their own.
This is O(n^2) in the number of files. Django has 1800 files. How much overhead does this add to processing that? Would probably be better to construct a map from file to source unit and then check all files against that. Also, why does there need to be a new function? Doesn't pythonSourceFiles() do what we want, as far as enumerating Python files?