1. Use explicit commands here for better tracing even if it requires
spelling out '/usr/local/bin/git' a number of times.
2. Use the functionality that the Shell class has to offer now.
3. Use -C for changing the git working directory.
4. A bit of style left and right.
o add missing dependancy in Makefile
o add branch in Model
o implement backup() method, which is responsible for setting up a git repo and pushing it upstream. The actual "git add+commit" is a responsibility of the syshook config event (todo)
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