Pull out query model in collections.
add query model to multicollection
add query model, add configuration management to graph components, fix re-rendering of several components
fix re-rendering of stack component

@gtrogers
@abersager
Add period tabs to overview graph.

@abersager
@gtrogers
Fix controllers + tests
Add tests for tab component.
Show tabs on per_authority and per_licence page
minor fixes to tabs styling
refactor spec/extensions directory
refactor query model
add 'duration' attribute to query model
add basic graph headline view to all pages
minor visual tweaks
remove unused statement
Merge pull request #75 from alphagov/add_monthly_graph_view

Add monthly graph view