Fix issue #302 - Standardize prop -> DOM attribute process

- attr="{1.2}" is now translated to attr="1.2" (numbers)
- attr="{true}" is now translated to attr="true" (bools)

Still a work in progress.

As I already tried to change the wrong things (esprima-fb), I want to make sure I'm changing the right things now :-).

What else do we want here? 
- make "undefined" and "null" the same as ""? 
- Objects are already being handled as desired I believe. 
- And data={} was out of the picture