Refactor breadcrumbs

Currently the trail of breadcrumbs involves logic spread across a number of areas. This attempts to consolidate and simplify it.

Some discussion around the classes created under ``app/domain`` could be useful; I ended up using a syntax along the lines of  ``DomainObject.new(params)`` rather than ``DomainObject.new(params).call`` which has been the convention so far with our service objects.

@andrewgarner @gjvis @jongilbraith 
Well, the only logic is constructor which ultimately returns an array of data. We could perhaps store the data in an instance variable and then delegate to that. Or just return the data