Upgrade to grails 2.3.7 and fix a couple typos

This pull request incorporates a few typo fixes in uninternationalized text, but more substantially a fix for https://github.com/DICE-UNC/idrop/issues/2 plus result of upgrade to grails 2.3.7 (that is, running "grails upgrade" in idrop/idrop-web on a system that has Grails 2.3.7 installed)