SA of the caller. This means we call out to the Emulab newgroup script
to create a group if it does not exist. We also have to reset the
groups of the GeniUser once we know the SA. 

Other small changes:

* Minor module shuffling.
* Use GetSiteVar() from emutil instead of libdb
* Get rid of obsolete code referring to the old reservation holding
  experiment.
* Cleanup logfiles in the workdir.
* Capture output from the mapper and reformat error logging to make it
  more apparent to the caller what went wrong.
* Change call to GeniSliver::Node->Create(); pass in the node object.