Allow deleting a list from Listrr without deleting it from Trakt.

[chazlarson]

Perhaps one uses the "name-based list" to set up a static list of things which won't be updated once created [something like some website's list of the 100 best horror movies or the like].

There's no reason for Listrr to keep updating it, but presently one can't delete the list from Listrr without also deleting it from Trakt.

This is an alternative to #124