Add shopping cart route + controller and specs.
Begin view work
Fix some bugs with the shopping cart controller, refactor the update method to take a more sensible params set.
Fix the partial to be a teensy bit less ugly.
update stale comment
Adds shopping cart specific JS.
Adds a new route.
Adds a job for zipping shopping carts.
Looks like i haven't been committing.  This gets shopping carts working.
Add working clear cart action.
Remove extraneous puts
Add a check that should disallow more than 100 entries per shopping cart.
Eliminate some unnecessary abstraction.
Eliminate some unnecessary abstraction.
Use send file instead of send data to stop sending empty .zip files.
Fix a typo, confirmation on delete request now actually appears.
Move directory clearing action into the controller.  Forces the app to block until the file is actually gone.  On even modestly large files we were getting back stale versions of the cart otherwise.
Update carts to be placed in tmp/carts/ and bound to session id rathern than the current user's NUID, which disallows unauthenticated use of the shopping cart.
Add a simple rake task for cleaning out shopping carts.  We'll want to daemonize this at some point.
Merge branch 'feature/shopping_carts_two' of https://github.com/nu-lts/drs into feature/shopping_carts_two

Mergin