* Add ability to control timeout when invoking tmcc, and whether to
  fatally die if tmcc fails. Related change was to allow more options
  to be passed into tmcc by way of an additional options argument.

* Change to pubkey handling. tmcd now returns a list of pubkeys for
  each login. The entire list is written to the authkeys files, and
  the old is backed up (with mod time preserved).

* tmcd now returns a serial number for each use to indicate when
  user info has changed (via the web pages). Only users with updated
  serial numbers get modified (and new authkeys file created). This
  should vastly reduce the passwd/authkeys churning on the ron nodes,
  which periodically check for account updates. The little db file now
  records the serial number too.

* Change to os_usermod; Change the actual password string! Was not
  doing that before.

* Conditionalize all the tmcc.foo stuff that Shashi added; don't want
  any of this on remote nodes yet.

* Remove a bunch of printfs to reduce output clutter.