Support for collection-helpers

collections.coffee
```coffeescript
Profiles.helpers
    user: ->
        Meteor.users.findOne @userId
```
list.coffee
```coffee
Template.listProfiles.helpers
    settings:
        fields: [
            {key: 'user.emails.0.address', label: 'Email'}
        ]
```

Patch to make dot notations works with collection-helpers members