Returns a string of option tags for pretty much any country in the world.
#### country_select
Returns select and option tags for the given object and method, using country_options_for_select to generate the list of option tags.
#### option_groups_from_collection_for_select
Returns a string of `option` tags, like `options_from_collection_for_select`, but groups them by `optgroup` tags based on the object relationships of the arguments.