[Hawkular-dev] how to avoid required sysprops

[Juraci Paixão Kröhling]

Before the keycloak.server.url, we did have a feature where we would try 
to determine the IPs and ports that we are running. The problem is that 
a Keycloak "ticket" issued via "localhost:8080" cannot be validated by a 
server on "127.0.0.1:8080" (there's an "issuer" field on the OAuth, and 
any mismatch there *has* to fail the validation).

So, we need a "consistent" way to reach the Keycloak server, hence the 
property. We could try to tweak the port offset, but that solves only 
part of the problem.

Note also that Keycloak *will* be somewhere else in production 
environments, so, we do need this property in a way or another. What we 
could improve, though, is how to make the "default" value smarter.

If we have some sort of installer, do we assume then that users won't 
change the port offset? If so, I could make a "first boot" routine that 
would set the default value of the property to the appropriate offset, 
while leaving the host as "localhost".

- Juca.