Fix request aborting and schema-relative urls

First about aborting. This is unexplainably magic. I can only suppose what IE require closure in this place. But this is fact: requests with `onprogress = $.noop` fails in many cases (long request, long response, slow connection).

Schema-relative urls required because «Requests must be targeted to the same scheme as the hosting page» is [one of XDomainRequest limitation](http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx). As I can see schema-relative urls works fine in this place.