remove namespace from symbol before sending to dash

Removes the namespace qualifier from the search string before sending to dash. For example, if you required ```clojure.string :as string``` and then use ```string/join``` in your code, when you hit _Ctrl-c,d_, it'll search for ```join``` in *clojure* docset (instead of searching for ```string/join```, which doesn't return any results).

It's a very basic fix (the proper fix will need to use cider's functions to resolve the _thing-at-point_ to canonised form), but it works.