Read default discovery address from System property

We have different environments of the same application (test, QA, production) and they should not use each others JMS provider.

I prefer to set the discovery address through a system property to have it set once for all brokers in the JVM.

Does it make sense?
JBoss does something similar. (but they have a range of addresses)

I know it's possible to set it in the config file.

Also removed a duplicate "start - myHost"
Or did that make sense?