fixed #1830: Using JS::CompileOptions::setUTF8(true) to compile script.

Also,
* Automatically generating jsbinding for `cc.Node.getChildren` since `ccarray_to_jsval` does this stuff.
* `js_get_or_create_proxy` returns NULL rather than making an `assert` when the native type  can't be found. This is used in ccarray_to_jsval and ccdictionary_to_js to check whether the value is an js - native glue object. If not, go to the logic of creating normal js objects.