Makes the InterchangeableListAdapter useable with set and map datatypes.

I was going through [this tutorial](https://github.com/krisc/events/blob/master/tutorial.md) and thought it would be neat to be able to feed the (def listing (atom (sorted-map))) directly to a list-view. This of course crashed my application until I modified the adapter itself. Now you can do this:

```
(def listing (atom (sorted-map))) ; { "20140722" [["At your place" "Party] .........]
                                  ;   "20140723" [ .... ]
                                  ;   ...... }

(defn main-layout [activity]
  [:linear-layout {:orientation :vertical}
   [:list-view {:adapter (ref-adapter (fn [] (make-ui [:text-view {}]))
                                      (fn [pos view parent [date events]] ..... )
                                      listing)}]])
```