Remove try. Rewrite wrap. Don't swallow exceptions. Remove capture, use push instead.

So I am trying to add JS notifier to Airbrake and it hardly works. These are small changes I made to local copy:
- removed try. I don't want us to recommend calling functions via Aibrake.try(funcname, arg1, arg2). I would hate such code.
- rewrote wrap. Now it can be used like this:
    jQuery.fn.ready = Airbrake.wrap(jQuery.fn.ready);
- removed capture function. Why do we have both capture and push, but only push is always available?
- copy client's wrap function in case client modified it. Spent few hours debugging this.
- don't swallow exceptions. Yes, we should not raise exceptions there, but that does not mean that we should silently ignore them.