API extension hook "getIsModifiedOnStage" renamed to "updateIsModifiedOnStage", also moved "getIsDeletedFromStage", "getIsModifiedOnStage" and "getIsAddedToStage" from SiteTree class to Versioned data extension class
* Added Created field to File/Image editor
* switch default input value to null
Fix react errors and added a field description
* API Use new DBField::getSchemaValue()
Introducing <Tabs> component based on react-bootstrap
Better support for nested fields in FormBuilder
Tweaks to get FormBuilder working with frameworktest BasicFieldsPage fields
Added exception in FormBuilder when Component is defined but not found
Added check in SingleSelectField for empty value before adding one in
Added temporary workaround for CompositeFields with no name (another story to address the actual problem)
Added asset_preview_height for File image preview, matches the defined CSS max-height
Added documentation to DBFile::PreviewLink() method
