Small changes to accomodate the an import change in nrmllib
Merge branch 'read-logic-trees-from-db' of https://github.com/larsbutler/oq-engine into streaming-xml-writer
Merge branch 'master' of github.com:gem/oq-engine into streaming-xml-writer
Merge pull request #1258 from gem/streaming-xml-writer

Changed an import from nrmllib