Simplified several things - got rid of some unnecessary checks that were
actually causing problems.  Moved IP alias creation to appropriate
library entry points (since they are now ephemeral constructs).  Fixed
vlan interface creation/destruction to better support lans.  Changed how
the vnode's state (existence, running, stopped, etc.) are checked.  This
should fix stale resource cleanup and is also more lightweight.  Finally,
keep the lock even while retrying deallocation when volume is busy.