getGitCommit in rmg.main doesn't know where it is running from

[rwest]

It would be better if it used the path to file to find where to run the git log command.
Currently, if you run it from somewhere outside of the main RMG folder, it doesn't work.
(eg. if you do python $RMGpy/rmg.py path/to/input.py and you are not currently in $RMGpy)

[rwest]

Think this'll be closed by 109f369cc6ea3063d3d6e4c87d30a7fa81b8e339

But another option would be to use git --git-dir /foo/bar/.git log