Added support for IE's handling of 204 status codes where it returns 1223 instead of 204.

IE 8 and 9 can not handle HTTP responses with status code 204 (No Content) properly. Code 1223 will be used instead.

Now, when this happens, we map it to 204.

This is a know bug, which is fixed in IE10 and is documented here: http://stackoverflow.com/questions/10046972/msie-returns-status-code-of-1223-for-ajax-request

I've tested this in IE 8 & 9.