hoodie.store.find('test', 'nope') to reject with Error Object and correct message

it currently rejects with a string: `HoodieNotFoundError: "undefined" with id "undefined" could not be found'.

Instead, it should reject with an instance of `HoodieNotFoundError` and the properties:

```js
{
  name: 'HoodieNotFoundError',
  message: '"test" with id "nope" could not be found',
  type: 'test',
  id: 'nope'
}
```

When fixed, enable the according tests in https://github.com/hoodiehq/hoodie-integration-test/blob/master/tests/www/api/store.js.

It's the same with all other store methods, probably all rejected promises in general. Hoodie must always reject with an error object