show git-out and git-in (ahead and behind) commits

We should be able to show to the user the commits that they are ahead or behind of the remote tracking branch. The git command for this purpose is:

Git OUT

 git log --pretty=format:'%C(yellow)%h%Creset: %Cblue%an%Creset %s' --abbrev-commit --graph @\{u}..

Git IN

git fetch && git log --pretty=format:'%C(yellow)%h%Creset: %Cblue%an%Creset %s' --abbrev-commit --graph ..@{u}

Of course, we should use gitpython for this purpose and use `iter_commits` when the repo is ahead or behind. This should also have a frontend ticket where the output is shown to user.