Swith the pygit2 as back-end for the git/python interaction
Rework the way the system command are handled

Use the popen module instead of the system call and print the output to the logs if the return code is not 0.
Fix the docommit flag -- now it will only commit when there is something to commit
Formating change

Use brace to be able to have the import over two line and thus less than 80char long
Port to recent pygit2, perform one commit per change and make the file pep8 valid