fix fakeServer.respond() in IE8 by properly allowing queue to be spliced

The request `queue` was not being properly emptied in IE8 due to the ECMA3 required argument for `deleteCount` being omitted. See the [MSDN documentation] for more details.

[MSDN documentation]:http://msdn.microsoft.com/en-us/library/wctc5k7s%28v=VS.85%29.aspx