fix(form): Fix prop-types validation issue

Author: David Emory

lib/components/form/date-time-preview.js

@@ -9,7 +9,7 @@ class DateTimePreview extends Component {
     compressed: PropTypes.bool,
     date: PropTypes.string,
     departArrive: PropTypes.string,
-    editButtonText: PropTypes.string,
+    editButtonText: PropTypes.element,
     time: PropTypes.string,
     onClick: PropTypes.func,
     routingType: PropTypes.string

lib/components/form/settings-preview.js

@@ -9,7 +9,7 @@ class SettingsPreview extends Component {
     // component props
     caret: PropTypes.string,
     compressed: PropTypes.bool,
-    editButtonText: PropTypes.string,
+    editButtonText: PropTypes.element,
     icons: PropTypes.object,
     showCaret: PropTypes.bool,
     onClick: PropTypes.func,