[TIMOB-19632] Alloy widget always converts argument type to string

Pass the argument as follows will result in all arguments - i.e ratable, rate being converted to String type in widget.js

<Widget src="com.tourist.components.rating" ratable=false rate=3 size=20 bottom=55.5/>

However, if I attach arguments to a view as below

<View id="my_view" ratable=false rate=3 size=20 bottom=55.5/>

_.isBoolean(my_view.ratable) === true; //true!

I think we need make widget behave the same as view in terms of arguments type.