Allow for overriding the project root from `/app` to something else,
such as `/var/www/html`.
The default is set within a new `build.defaults.yaml` file which the
project specific file is merged into.
Fixes#27
Allow for setting a `docroot` directory for Drupal projects.
By default, I've set this to `web` as that's what the Drupal Composer
scaffold projects use, but other platforms such as Acquia Cloud hosting
use `docroot`.
This is how it can be configured in `build.yaml`:
```yaml
drupal:
docroot: docroot
```
Fixes#2
- Allow for setting a database `type` and `version`.
- Don't add a `database` service to docker-compose.yaml if there is no
key within `docker-compose`.
Fixes#14