Adds delicious history.pushState goodness

With a smooth crème anglaise topping.

Scrapped gets a new fakeHistory function in handy_functions.js, which
accepts a url, and an optional boolean that determines whether to
execute a pushState or a replaceState.

Also moves Scrapped.currentFolder and Scrapped.currentProject to new
locations in the Scrapped.appstate object, just to be more orderly.

Rails:
Adds a default scope to Item model that rejects trashed items, and
removes many of the .where(trashed: false) in the ItemsController.

Deletes the favorites folder in views, because it hadn't been used for
a very long time.