Add HPIs line graph
move and amend regional_hpi single page stagecraft_stub
Add the concept of a module_banner to wrap modules

On the housing dashboard, we'll use this as a warning. This commit just
adds a default banner, which is grey.
Add red restricted data banner

This includes a new grunt task for Spotlight assets in development
and production.
Switch more info callouts from auto to 100%

I can't remember why we were using auto (pretty sure there was a reason),
but it's broken now. Switching to 100% fixes the issue.
Style tweaks to module_banners for small screens

Removing the float: none; on small sections may make small screen
modules break, but we don't have any of those yet.
Move image to assets directory