Parse translated and nontranslated strings

This updates translate-tag.rb to parse all strings. This means that
we can add items such as {{ site.name }} into the source strings
and the plugin will do the rest. We no longer need hacky a
hacky workaround.

_plugins/translate-tag.rb

@@ -33,11 +33,12 @@ module Jekyll
       if page_language.nil?
         Weblate::SourceFile.add_entry(weblate_id, text)
 
-        text
+        Liquid::Template.parse(text).render(context)
       else
         translated_string = site.data["languages"][page_language][weblate_id]
 
-        translated_string.nil? ? text : translated_string.strip
+        translated_string.nil? ? Liquid::Template.parse(text).render(context) 
+                               : Liquid::Template.parse(translated_string.strip).render(context)
       end
     end
   end