Organisations on subsector pages (not ready for merge)

Opening this PR for discussion; it's not ready to merge yet.

Review of the approach taken (both for testing this, and for implementing the new presenter and controller method) would be helpful - but the actual displayed output isn't yet correctly formatted.

This implements https://www.pivotaltracker.com/story/show/75807888, which adds a list of organisations which are related to the content in a specialist sub-sector.  This list goes in the metadata section - except that the `collections` doesn't app doesn't have a metadata section yet.  I've tried copying the relevant bits from whitehall to make a working first cut of a metadata section, but am bogged down in sass and lots of module imports.  I think I need to pair with @edds for a little bit to get this finished.

So far, an example sub-sector page looks like this at the top:
![screen shot 2014-08-07 at 12 46 42](https://cloud.githubusercontent.com/assets/73564/3841208/8e70145c-1e28-11e4-9025-6ad08395c7fc.png)

I think the whitehall metadata section also has some special analytics tracking enabled, which we should probably copy.

 - [ ] Fix alignment of "From:" and content of the list of organisations.
 - [ ] Fix font size of "From" and list of organisations - it's visibly different than that used on whitehall pages currently, I'd expect it to be the same.
 - [ ] Ensure proper analytics are being sent about clicks on the organisations (same as whitehall).