Revision 642

In net-scripts/net.modules.d/ifconfig:
- Simplify ifconfig_is_up()
- Fix ifconfig_get_aliases_rev() to actually work... you can't
  specify an interface name to ifconfig if you want to see the
  aliases.
- Workaround a couple ifconfig bugs dealing with aliases
- Correct a return status in ifconfig_interface_del_addresses()