Cache Buster
Simply adds a tag which applies to a cache buster to any asset.
Usage
<h1> Homepage </h1>
<img src="http://example.com/some/external/image.jpg<r:cache_buster/>">
Configuration
# file: :radiant_root/config/initializers/radiant_config.rb
Radiant.config do |config|
config['cache_buster.timeout'] = 1.day
end