[WIP] #354 Information Architecture Review

__Do not merge yet as I'm waiting on #300 to be in master.__

I want CKAN 2.0 to be clearer. I want it to be more consistent and concise in the way that it communicates context. The changes mentioned below don't take any features away, they just make them a little simpler to understand.

Here's a brief overview of what I'm going to do:

* __Dataset page:__ There should be more like the group and user pages in terms of heir-achy
* __Parent context:__ There needs to be another UX method of showing that an object has a one way relation to a parent object (e.g. a dataset belonging to a organization) See the page header in http://okfn.johnmart.in/prototypes/#?project=harvest_source&view=edit for example of implementation
* __Re-jigged header:__ The main navigation doesn't feel "solid" enough. Also there's a lot of noise around the search box.
* __Page tweaks:__ There are also a few other pages that fall out of a decent iA structure that I'd like to rationalise (like the dataset page)

See #354 for context