Create proxy method to close empty dropdown

Proxy method to facilitate plugin overrides

We need to prevent selectize from closing the dropdown when first triggered even if there's no options available.

We need to show the dropdown to display a custom message to the user to inform him that there's no data available with his current filters.  He also needs to see the custom "Add" button that we've injected with a plugin in the dropdown.

I figured that a proxy method that could be overriden by a plugin would be better that overriding the whole "refreshOptions" method.

If there's a better way to achieve this, i'm open to suggestions