[Hawkular-dev] RfD: Installer

Hey, while the All In One zip works well for demoing, using Hawkular in a more serious scenario requires a lot of options and settings * External C*: $CASSANDRA_NODES and -Dhawkular.backend=remote * Binding to non-localhost: -b a.b.c.d and -Dkeycloak.server.url=http://a.b.c.d:8080/auth * Adding jdoe to a dist build: -Dkeycloak.import=./standalone/configuration/hawkular-realm-for-dev.json * Using an external RDBMS for keycloack users: "before the server first boots, the `KeycloakDS` on `standalone.xml` should be changed to point to an external database." (this applies when using the embedded KC and not a separate standalone one) * If not using jdoe above: setting user/password for the internal agent after a user was created * Dorking around with standalone.xml to chose up a mail server * Setting other java opts all the above involve a huge amount of manual steps and configuration changes. I think it is thus time to introduce some sort of installer or config script that is able to make the changes. I think there is meanwhile even a cli mode that can apply the changes (to standalone.xml) on a non-running server. Some options could be set in env variables or directly applied to the standalone.xml. If we still need to supply env-variables we may potentially also create a start script from the installer, which sets the variabls and then calls standalone.sh