Page Builder autocomplete fields

• Page Builder extension clean up for new fields added in 2.6-2.7 versions of SiteOrigin Page Builder
• Posts search/selector based on Select2
• Terms search/selector based on Select2

Usage example:

'posts' => array(
		'type'       => 'select-posts',
		'post_types' => 'page,employee',
		'label'      => __( 'Posts', 'boilerplate' ),
	),
'terms' => array(
		'type'       => 'select-terms',
		'taxonomies' => 'category',
		'label'      => __( 'Terms', 'boilerplate' ),
	),