Bug 974867 - [MMS]Auto suggestion for email address r=Julien

https://bugzilla.mozilla.org/show_bug.cgi?id=974867
Please, we can do a lot better than this. For example:

```javascript
var props = ['tel', 'givenName', 'familyName'];
if (Settings.supportEmailRecipient) {
  props.push('email');
}

return this.findBy({
  filterBy: props,
  ...
}, callback);
```