The default is /usr/share/pungi/multilib/, pass --multilibconf to
override this.
This also adds multilib.init() so that an import of multilib doesn't
immediately setup the classes.
(cherry picked from commit 234524296fd53871aed64690cf6a7d5849ca154a)
for https://fedorahosted.org/rel-eng/ticket/6008 refacter how we deal
with the data that feeds into .treeinfo
Deprecate --name for --family
Deprecate --flavor for --variant
rather than using --name as the iso base name use the value of
family if there is a variant add it with a - as the seperator
