lonestar host file: explicitly list login node hostnames in host aliases

With this change, we don't have to rely on the (apparently faulty)
matching logic in config.py to determine which host-config file to load
for Lonestar4.
config.py: ensure build options are sorted after host build config applied
option.py: handle newlines in option documentation
command.py: fix support for negation of default options

This commit fixes two issues:

  * the negation flag wasn't being stripped from the option name prior
    to that name being stored

  * negated options were being applied _before_ the host config (which,
    of course, negates the whole point of negated options...)
{command,core}.py: allow selective-purge by build name or ID
core.py: add missing comma in PackageSet.__init__ (introduced in @c5f494b)
{core,command}.py: pass force flag through to definition.build as kwarg