Expose resetSearchInput as global

[amcdnl]

I propose we expose resetSearchInput option as a global property. IMO you would probably want this to be true but it is set to false by default, which is fine but having to ability to set it globally is important. Example usage:

app.config(function (uiSelectConfig) {
    uiSelectConfig.theme = 'select2';
    uiSelectConfig.resetSearchInput = true;
});