`g` with no arguments is `git status` and with arguments acts like `git`

`g` with no arguments is `git status` and with arguments acts like `git`. This won't affect your current way of doing things, but only adds more function to `g`, making it easier to view git status -  and a good way to save keystrokes. Got this idea from [@thoughbot/dotfiles](https://github.com/thoughtbot/dotfiles).