install script restructure

I got rid of plugins we're not using. Then, restructured the script such that the procedure operates in a way that will be a little more friendly to oo-installer. Specifically:

* The major sections are broken into bash functions (so they can be specifically run with CONF_ACTIONS) and delineated in the output so that progress can be tracked and partial re-run is possible.
* All of the subscription mgmt is done, then all of the package installing, then all of the configuring. This way you can re-run the package install (the most likely part to fail), without configuration having occurred that could break things (e.g. nameserver, sshd, etc.).