consumer should be able to set dropdown button and split button button t...

Button type set by the consumer are not honored for dropdown menus ( buttonDropdown() & splitButtonDropdown() ), but should be as both link buttons and HTML buttons are valid inside these button groups in Bootstrap 2 & 3.  Also changed to default as HTML buttons rather than link buttons to more closely align with Bootstrap's baseline samples.  Fundamentally, these changes could be applied to the /master branch as well.