Support single-select dropdown where filter keys are different

[wcurtis]

Problem

We've got a dropdown that should be single select, but the specific filters have different keys (is_guest=true, and is_member=true, etc).

Proposed soln

Add a new action in https://github.com/wcurtis/ember-list-card/blob/master/addon/components/list-card.js

Currently we have 3 actions the dropdown filter can call:

• addQueryToken
• removeQueryToken
• replaceQueryToken

A new one that lets dropdown specifiy which tokens to add AND remove at once could work

• addAndRemoveQueryTokens(tokensToAdd, tokensToRemove)

[wcurtis]

/cc @vladucu