Move bulk progress script into a module

* Switch from inline JS to a module
* Pull URL from data attribute
* Switch from setInterval to a timeout that gets set once the previous
request is complete
* Reduce scope of jQuery selectors to just the element we’re looking at
* Create a spec

Not yet handling errors, updating aria values or handling completion
Clean up background bulk add modal styles

* Take out inline styles
* Use default inherited styles where possible
* Make some specific styles for this modal
Add an ok button to bulk add modal

* Refactor modal CSS that deals with absolutely positioned close buttons
* Make the modal-saved-mappings CSS re-usable, and remove the specific
font-size: 80% rule on the glyphicon
Show a modal success state when all mappings added

* When done matches total, stop making requests, show a success state
and shut down the module
* Use jasmine clock to avoid having to wait 1 second for each timeout
test
Merge pull request #263 from alphagov/background_bulk_add_modal

Refine background bulk add modal