Create .env file for the ports

- [ ] - A new, gitignored file called`/dev-overrides.env` will allow developers to override env variables in development environment.
- [ ] - This override system should not affect test environments.

For example, if dev.env contains:

```
FOO=1
BAR=2
BAZ=3
```

And `dev-overrides.env` contains the following:

```
FOO=2
```

Then the result will be

```
FOO = 2
BAR = 2
BAZ = 3
```