v0.5.2

Enhancements:

• Added new layout for the UCF Post List Shortcode plugin, "news", which displays posts in a news-like layout with optional thumbnails, excerpt text, and subhead text
• Updated default excerpt trailing text from "[..]" to "..."
• Added utility function ucfwp_get_excerpt() for retrieving a post's excerpt with an optional custom length
• Upgraded packages to latest versions, including the Athena Framework