pass the app to getModel when constructing a model from the options passed to a view

Models generally expect to have access to the app object, but if they're constructed from the options passed to a view they're currently missing the app. This is a quick fix for that by passing options.app (which is required) to the modelUtils.getModel function.
Even though the cases that currently call this function always have an options.app - we should probably verify that it's there.

```js
var opts = { parse: true }
if (_.isObject(options.app)) { opts['app'] = options.app; }
options.model = modelUtils.getModel(options.model_name, options.model, opts);
```