Various things modified in the tools

1) ValueErrors raised by parse_limit_node() are now caught and warned
   about, rather than causing an error.  This should help users
   understand the source of errors.

2) The deprecated parse_config() has been removed.

3) The console script stubs have been folded into a new ScriptAdaptor
   class which uses decorators to identify arguments.  This allows
   the functions to be renamed from their underscore variants
   (assignments are included for backwards compatibility).  The
   major advantage of this is improvement in the maintainability by
   reducing duplicated code.

4) Most of the original tools.py test suite has been rewritten.  This
   includes the introduction of compare_xml(), shamelessly adapted
   from nova.tests.matchers.XMLMatches (hey, I wrote it to begin
   with, and it is under the Apache license...); this improves the
   XML comparison tests.

Still to do: Rewrite the tests for setup_limits(), dump_limits(), and
remote_daemon().
Update tox.ini now that E123, E125, and E126 are resolved.