Activity Stream

Branch for activity stream commits. Still WIP. Will post comments in https://assembly.com/buckets/bounties/82 to keep it all in one thread.
We could do that and I thought about that, too, but Rails taught me that this does not belong into the model. :)
I think we should rather look into a better overall approach for building links that ideally makes use of the routes definitions and that cannot just be used for activities but for all links in the app.
One option would be building our own link_to helper that uses `Chaplin.helpers.reverse`.
But then you made a very good point where it would be nice to be able to use those helpers in emails as well (and we may not just send emails for activity stream related stuff?).
Emails are just views as well, at least in the Rails world, so that's why you can use view url helpers there just as in any other views. I guess it would be nice if we could follow that philosophy in the Buckets stack as well.
For one I guess for html emails we'll be using something like horseshoe so that we can use handlebars templates?
And then I did some quick googling about reusing Backbone/Chaplin routes on the backend.
If found this post from Airbnb (http://nerds.airbnb.com/weve-launched-our-first-nodejs-app-to-product/) who created https://github.com/rendrjs/rendr which has a ClientRouter and ServerRouter which reuse the same route definitions.
So I think we should also go into that direction, what do you think?