Dlc 17 - Listings UI [IN-PROGRESS]

@Saityi make a pull request next time and tag me. Don't be shy :)
Cool! `redirect_to current_admin` works perfectly. I didn't like `redirect_to :back`, it was just all I could find; this is more in line with what I had originally intended. This also allows the temp fix in https://github.com/sourlows/dlc_web/blob/dlc_17/spec/controllers/listings_controller_spec.rb to be removed -- it doesn't need to know the http referrer because it's not redirecting to it.

 Much better! :)