Set "Displays" (manual) preferences

I haven't found a way to automate this so instead I have to do this manually.

```
In Preferences > Displays > Built-in Retina Display

* Select "True Tone"
* Select "Resolution: Scaled" and a 1440x900 resolution
```

These settings don't seem to be modified even after I save the output of `defaults read` before _and_ after changing it.