Prevent spurious timeouts in a local environment when using IE8/9, SockJS and the `jsonp-polling` transport

This adds the ability to automatically apply custom patches to the SockJS client that we ship with Primus.
This also adds a patch for the `utils.countRTO` method that the SockJS client uses to calculate the retransmission timeout.
The reason for this patch is explained in details here https://github.com/sockjs/sockjs-client/pull/161.