API Escape form validation messages (SS-2013-008)
FIX Auto-escape titles in TreeDropdownField

Related to SS-2013-009. While the default "TreeTitle" was escaped
within the SiteTree->TreeTitle() getter, other properties like SiteTree->Title
weren't escaped. The new logic uses the underlying casting helpers
on the processed objects.
FIX Escape breadcrumbs in SecurityAdmin (SS-2013-007)
Check for jQuery in Behat tests

Identified as one potential cause for flickering tests
on our own Selenium box.
Merge branch '3.1.0' into 3.1
Merge remote-tracking branch 'origin/3.0' into 3.1