deis create in a non-git directory should run with --no-remote

As reported in https://github.com/deis/builder/issues/499, the Heroku client will run `heroku create` with `--no-remote` if the directory we are running in is not a git directory:

```
[~:dom] ⚡ heroku create
Creating app... done, ⬢ thawing-forest-56676
https://thawing-forest-56676.herokuapp.com/ | https://git.heroku.com/thawing-forest-56676.git
[~:dom] ⚡
```

Whereas with the `deis` CLI, this does not happen:

```
[~:dom] ⚡ deis create
Creating Application... done, created haptic-farmland
Error: Error when running 'git remote add deis ssh://git@deis-builder.cluster.fluid.ly:2222/haptic-farmland.git'
fatal: Not a git repository (or any of the parent directories): .git
```

I'm not sure if this was "fixed" in later Heroku versions, but this wasn't the case a few years ago. We should try to mimic Heroku's workflow here, seeing how we are an "open source Heroku".