Add support for new attributes on latest DataChannel specification

[piranna]

According to http://dev.w3.org/2011/webrtc/editor/webrtc.html#peer-to-peer-data-api (June 3th), now DataChannels has removed the 'reliable' atribute and it's using ordered, maxRetransmitTime, maxRetransmits, protocol, negotiated and id. Reliable library should have a way to define them and work as spected on the new specification.