Store references to generated dom functions inside a hashmap as well

On two projects I'm working on that use quiescent, I prefer to work with a data driven ui structure (nested hash maps, or even hiccup). In these projects I actually store the UI structure in an atom and then simply call `render` on this structure whenever I want to update using react. This is quite hard to accomplish without first class namespaces. I'd like to see a change like this one that defines a hash-map called `defined-tags` this way I can more easily drive my render routines with data rather than canned functions. 

Example:
```clojure
(render {:type :div
              :contents [{:type :h2 :contents "Hello World"}]})
```

The function `render` can now be easily be built using the `defined-tags` hash-map, apply, and about 20 lines of code.