Ensure deleted assets are cleared

[karenmajewicz]

When I upload and attach an asset, a number indicator appears on the main record next to the "Additional Assets" side menu link. If I then delete the asset, this number does not change.

[ewlarson]

Replicated this issue locally and on geodev.

It happens if you use the back button to return to the show page, which renders the browser's cached version of the page with the false (1) number still present. If you do a reload of the page the number is correctly (0).

There might be ways to solve this with Turbolinks...