Defs should support other harmony features

[termi]

There is a major problem with using defs before traceur. defs not supported such harmony feature as destructuring and can't compile js with it.

I created a branch with destructuring, function rest parameter and function parameter default values supports.

One of the option is to support destructuring and default values, but not to touch it

[olov]

defs isn't a general purpose ES6 to ES5 transpiler but feel free to extend or build other things on top of it! Regarding understanding destructuring (but not transpiling), that may happen but only after official support is implemented in Esprima.