[Hawkular-dev] RfD: Installer

[Heiko W.Rupp]

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