Enabling of developer properties in the environments.yml

It would be nice if rays could be configured to ask Liferay to load the portal-developer.properties file when starting the Liferay service. In the past I've prefixed the following JAVA_OPTS snippet in front of the tomcat startup script.

```
JAVA_OPTS="$JAVA_OPTS -Dexternal-properties=portal-developer.properties"
```
