Assignment to os.environ was introduced in
ddd77222 but can have side effects
and is superseded by getCleanEnvironment

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.

also removed related tests

Conflicts:
	slapos/grid/SlapObject.py