Modified version of snmpit to be run as a "feature" while
testing. Changes include: * syncvlans option that compares the switches and the DB and makes everything consistent, including creating backing DB objects for the dozens of hand created vlans, since all vlans must have a DB object so that vlan tag reservations can be consistent across all stacks. * Clean up the tag stuff a bit. No longer store tag in the lan_attributes table since that is a transient table, prone to getting out of sync with reality. * Changes to how the set of devices in a stack is chosen; ensure that we do not reference switches that are not needed (no ports on that switch and does not traverse a trunk on that switch). This should allow us to move the Backbone switches back into the Experimental stack, without fear that normal swapin will block cause the long distance links to those switches is down.