Pressflow 7.31

Cherry-picked changes from Drupal core, 7.30...7.31. This security update fixes [SA-CORE-2014-004](https://www.drupal.org/SA-CORE-2014-004)

Commands I used to generate this:

    git clone --recursive git@github.com:mparker17/7.git && cd 7
    git checkout master && git pull --rebase
    git remote add drupal http://git.drupal.org/project/drupal.git && git fetch drupal
    git remote add upstream https://github.com/pressflow/7.git && git fetch upstream
    git merge upstream/master && git push origin master
    git checkout -b pressflow-7.31
    git cherry-pick 7.30...7.31
    git push --set-upstream origin pressflow-7.31

Happily, there were no merge conflicts.

Reviews welcome!