IA Pages Index - update layout to match the mockup

@russellholt @jagtalon 

This will be the main PR for the new IA Index layout. As for the plan, I've done the basic two-panes layout and I will then go ahead with the right pane, which still misses topics and templates, and with the general functionality (filtering etc).

@jagtalon, please feel free to begin working on the left pane (the IA list) layout by branching off origin/iaindex_new and creating a PR to this branch.

If you have any questions, suggestions and/or critiques please let me know!

Screenshot:
![screen shot 2014-12-04 at 15 00 48](https://cloud.githubusercontent.com/assets/3652195/5377129/a4cdebc6-807e-11e4-9db6-b37b92f15312.png)

I see that cut off anyway on my screen. We can adjust the max-height value or we can find a good alternative, just don't know what that would be.
I know the topics and templates divs should be dropdowns, but if they're both open they get cut off