Abort a request. If the request parameter is not specified all open requests will
be aborted.
@param {Object/String} request (Optional) The request to abort
function(request){
        var me = this,
            requests = me.requests,
            key;

        if (request) {
            if (!request.id) {
                request = requests[request];
            }
            me.handleAbort(request);
        } else {
            for (key in requests) {
                if (requests.hasOwnProperty(key)) {
                    me.abort(requests[key]);
                }
            }
        }
    }