Quality Control (qc) Command

 
Implementing qc command. pyflakes and pep8 are working OK. pylint option raises an error currently. TODO: Add function to git_tools.py to return list of files that have been modified. Us this function to implement '--changes' option and only run tests for modified modules.
I would also make these per checker: pep8-threshold, pylint-threshold etc as they are all very different things