Process SQLException.getNextException

The actual cause of a SQLException is usually hidden in Exceptions got
by calling getNextException.

There was a out of disk error in postgres several days ago. The out of
disk message was not in the caught SQLException but in the
getNextException.
Merge pull request #597 from uwescience/slxu-improve-sql-exception-processing

Process SQLException.getNextException
Merge branch 'master' into slxu-fix-and-improve-deployment