Fixes some coding style issues in core.js. In jQuery.fn.ready(), simplifies the whole...

Fixes some coding style issues in core.js. In jQuery.fn.ready(), simplifies the whole code (for better backward compatibility) and removes redefinition of the function itself (in order not to clash with proxying). Also, in jQuery.when(), removes unnecessary closure and early rejection test and makes use of then instead of done/fail (better interoperability).