WINDUP-329  Bundle settings.xml and a build script

It's more convenient for the user to get the source and run build/build.sh than to follow build instructions and change files manually. There's no manual intervention needed if we make it so.
It will also make tests and CI more convenient - no need to create/edit local settings.xml.

This is how WildFly has it.
Alternatively, we could add the repo to pom.xml - just like JBoss Developer Framework has it now.