New computed property: uniquely

Wraps up a common pattern used in charts for building a a string that
incorporates the ember guid

ui/app/utils/properties/uniquely.js

@@ -0,0 +1,12 @@
+import { computed } from '@ember/object';
+import { guidFor } from '@ember/object/internals';
+
+// An Ember.Computed property for creating a unique string with a
+// common prefix (based on the guid of the object with the property)
+//
+// ex. @uniquely('name') // 'name-ember129383'
+export default function uniquely(prefix) {
+  return computed(function() {
+    return `${prefix}-${guidFor(this)}`;
+  });
+}