[SSG] Stata has been upgraded to version 12 on all SSG nodes

We have upgraded Stata to the newer version on all nodes. New features are listed at http://stata.com/stata12/.

For a transitional period, the older version 11 will remain on the servers, and is accessible from the command line as '(x)stata11(-mp)'. Currently running jobs that used Stata 11 will continue to run, but all new jobs will use Stata 12.