[Feature request] Automatic deis profile selection based on git remote

It would be great if the deis cli could automatically lookup the correct deis profile based on the git remote, either by enumerating the existing profiles for a matching controller url or by using a special naming convention for profiles.

For example let's say the controller is at `deis.staging.example.com` then the deis cli could look for `~/.deis/staging.example.com.json`.

The remote to use for lookup would default to `deis`, but could be overridden using a global `-r`/ `--remote` option, so you could do something like:

```
deis ps # connect to deis cluster from 'deis' remote
deis ps -r staging # connect to deis cluster from 'staging' remote
deis ps -r production # connect to deis cluster from 'production' remote
```

If an environment variable `DEIS_PROFILE` is set or if `-c`/`--config` were to be given, these would take precedence over the automatic lookup based on the remote.

Having this feature would greatly reduce the friction when working with multiple apps on multiple clusters or same app on multiple clusters, where it currently can happen very easily that the wrong deis profile is used (eg. scaling down production instead of staging).