message: filtering by bool is dicey since filters are coerced to strings, using `exists` instead
diff: @@ -17,7 +17,7 @@ export default Component.extend({
  availableTypes: computed(function() { return []; }),
  loadAvailableTypes: task(function * () {
  - let types = yield this.get('store').query('content-type', { filter: { not: { 'is-built-in' : true } } });
  + let types = yield this.get('store').query('content-type', { filter: { 'is-built-in' : { exists: false } } });
  this.set('availableTypes', types);
  }).on('init'),
  