#178. Added _drupalgap_form_element_items_load(), _drupalgap_form_ele…

…ment_item_load() _drupalgap_form_add_another_item(), drupalgap_form_get_element_container_class(), drupalgap_form_element_item_create(), drupalgap_form_local_storage_save(), drupalgap_form_local_storage_load(), _drupalgap_form_render_element_item(), _drupalgap_form_element_items_widget_load(), _drupalgap_form_element_items_widget_arguments(). Changed drupalgap_form_load() to use drupalgap_form_element_item_create(). Changed drupalgap_form_load() to use drupalgap_form_local_storage_save(). Changed _drupalgap_form_render_element() to use _drupalgap_form_element_items_load() and _drupalgap_form_render_element_item(), it also places an 'add another item' button on unlimited value field elements. Changed _drupalgap_form_submit() to use drupalgap_form_local_storage_load().