install: improve cartridge selection

Premium cartridges (currently jbosseap, fuse, and amq) are those that
require an extra subscription beyond the standard OSE one. This being
the case, and because oo-install does not yet have a method of selecting
appropriate subscriptions and cartridge sets per host, we should not
default to trying to install premium cartridges.

The CONF_CARTRIDGES parameter defaults to "standard" (which means none
of the premium cartridges) and there are some new aliases available.
Premium cartridges can be specified this way or installed later.