Mass upgrade: moving from slapos_pdm bt and going through Hosting Subscription rather than Software Instance

This should disappear in the future. But it allows to make the system work for now.

BUT it prevents easy debugging, because it is reset
each time by slapformat.

Conflicts:
	slapos/cli/register.py

this retains comments and avoids issues with unicode, multiline values
(certificates) etc.etc.

both ipython and bpython are built and provided with slapos. bpython is the
default now, with colorful drop down menus. we can choose later.