Ability to configure post-action hooks for select controllers

[jayroh]

I'd love to be able to easily perform some commands after certain actions in the engine. For example:

1. Notify a slack channel when something in particular happens.
2. Track events to keen.io or mixpanel for purposes of analytics or data collection.
3. Send emails

... and I would not like to add those sorts of things into the engine proper. Monkey-patching seems a bit brittle and unadvisable, and filters require a little too much knowledge of the object graph. A contract stating that X objects or lambda's will be called per action, with Y objects, feels sufficient. Riffing:

Thredded.posts_create_hooks += [NotifySlackChannel]
Thredded.topics_create_hooks += [->(topic){ do_something(topic); }]

[jayroh]

Best bet for this might be to use ActiveSupport::Notifications instead of reinventing the wheel.

• http://api.rubyonrails.org/classes/ActiveSupport/Notifications.html
• http://apidock.com/rails/ActiveSupport/Notifications
• http://technology.customink.com/blog/2013/12/19/instrumenting-your-code-with-activesupport-notifications/