Add subtitle support to the following core blocks:
* my_network
* profile_search
* categories
* highlights
* slideshow
* article
* blog_archives
* featured_products
* feed_reader
* link_list
* location
* products
* profile_list
* raw_html
* recent_documents
* tags
Add subtitle support to the following plugins blocks:
* community_track: track_list
* container_block: container
* context_content: context_content
* display_content: display_content_block
* event: event
* gallery_block: gallery_block
* organization_ratings: organization_ratings_block
* people_block: people_base
* profile_members_headlines: headlines
* recent_content: recent_content_block
* relevant_content: relevant_content_block
* site_tour: tour
* sniffer: interests_block
Signed-off-by: Daniela Soares Feitosa <danielafeitosa@colivre.coop.br>