Checking the `style` attribute fails in JavaScript tests because the
browser converts colors to the `rgb()` format.
So we're testing the generated HTML in a component test while
simplifying the system test.
Now it's easier to change the investments filter. Previously we had to
go back to the budget index page, change the filter there, and then
select one heading.
Now the links to change the current filter in the budget index page
aren't needed anymore.
Now the banner component accepts either a banner or a section and loads
the banner if it's a section, so we don't have to add the `@banners`
variable in several controllers.
