use WP HTML5 markup for captions instead of Soil

Use add_theme_support to enable native HTML5 captions and add caption styling to wp-caption-text.

lib/init.php

@@ -23,6 +23,10 @@ function roots_setup() {
   // http://codex.wordpress.org/Post_Formats
   add_theme_support('post-formats', array('aside', 'gallery', 'link', 'image', 'quote', 'video', 'audio'));
 
+  // Add HTML5 markup for captions
+  // http://codex.wordpress.org/Function_Reference/add_theme_support#HTML5
+  add_theme_support('html5', array('caption'));
+
   // Tell the TinyMCE editor to use a custom stylesheet
   add_editor_style('/assets/css/editor-style.css');
 }