Make module_actions JavaScript more reusable

Rename module_actions to popover (à la iOS) so that we can use it
for a dashboard's related links. Include a basic first pass of
popover in related_pages.
Move popover related Sass into a single file

Use mixins to include it in multiple places.
Reorganise index.scss into logical groups

Also rename module_actions to module_more_info for ease of scanning.
Merge branch '62545960-hide-related-links-small-screens' of github.com:alphagov/spotlight
Add first version of "division of procurement" graph
Amend graph title
Update data URLs to match Backdrop
Add "total" option in Stagecraft stub, and "total" line to graph
Add tabs option to grouped_timeseries graph: update tests and stub data
Merge
Merge with master
Remove stray log statement
Merge with master
Fix ordering of line labels, set in Stagecraft stub
Handle valueAttr correctly on tabbed graphs.

* Provide an initial "value-attr" value in the Stagecraft stub.
* Update the collection's valueAttr on tab click.
* Ensure the line graph is rendered with the new attribute.
* Update Backdrop stubs and tests.
Merge pull request #125 from alphagov/g-cloud-division-of-procurement

G-Cloud division of procurement