Attempt to move Dbms handling into slave

Attempt to move Dbms handling into slave
* It typechecks and compiles... and looks like it ought to work
* `requestDbFoo' functions make an ad-hoc connection to a slave. There
  is much room for cleanup here.
* /Factored/ doIt function from `service' so that the Dbms message
  handling could be cut and pasted into the slave function
* Added Dbms.dbmsNode configuration option
* Note that dbms operations *always* occur on a slave now--if the
  machine is also the dispatcher node it will now need to run a slave
  instance as well