The list of plugins can now contain relative paths.
For example:
```yaml
plugins:
# will load myfirstplugin/plugin.js or myfirstplugin/plugin/index.js
- 'myfirstplugin/plugin'
# will load mysecondplugin/plugin.js or mysecondplugin/plugin/index.js
- 'mysecondplugin/plugin'
```